Kacsmar: Five biggest surprises of '12 NFL season Peyton's return, Saints sinking and those remarkable rookie QBs among our picks While the 2012 NFL season has offered many surprises from the rise of the NFC West, treatment of the replacement referees, and decline of the Baltimore defense, only a few continue to astound us halfway through the season. Here is a look at the top five, and we can promise there will be no mention of the New York Jets" overblown trade for Tim Tebow. Peyton Manning's comeback in Denver In less than half a season, Peyton Manning has returned from four neck surgeries and a year off at age 36 to transform the league's most run-heavy offense into the Denver Colts, and a major contender in the AFC as he campaigns for his fifth league MVP award. It's like Manning never left, and has somehow even improved his game after losing some of his fastball. Sure, it is easy to give the Denver Broncos credit for going after Manning, and to laugh at teams like Arizona and Kansas City for not pursuing him harder. But no one knew in March if Manning would have zip on his passes. Could he take a hit and get back up? No one at this stage of their career has ever tried to come back to the NFL from such serious surgery on their neck. This was not a torn ACL that players come back from all the time. The concerns were legit. After 13 seasons in the same city and offensive system, how would Manning react to so much change with mostly all new teammates, an outdoor team in the high altitude of Denver, a new division, and retooling things from the stone-age offense the team won with using Tim Tebow last year? Manning let Denver adapt to his offense instead of the other way around. It was not the fastest process and you can see even in Week 1 when things did not start well, Manning went to his comfort zone. That means using the no-huddle offense, the checks at the line, the bubble screen, the sprint-right option, the seam passes, the end zone fade and the pick plays. Manning and the offense has improved each week, leading Denver to a 5-3 record and is putting up some of the most prolific numbers in a prolific career. His completion percentage (69.5 percent), 20 touchdown passes and 108.6 passer rating are each the second highest he has ever had through the first eight games. In each of Manning's last five games, he has completed at least 70.0 percent of his passes and thrown three touchdowns. No quarterback in NFL history can match that, and Manning came up nine yards short in Cincinnati of tying the record for five straight games with over 300 yards passing and three touchdowns as well. Manning has also produced three comeback wins for Denver, including the wildest game of the season in San Diego when Denver trailed 24-0 at halftime before exploding for a 35-24 victory to take lead of the AFC West. While correctly predicting in the preseason that Manning's efficiency would increase both individually and for the Broncos in areas like third down and the red zone, the expectations of high-volume production were not there for his pace of 4,800 yards and 40 touchdown passes as well. With a favorable second-half schedule and continued rehab and progress, look for Manning to make a serious push for being named the league's most valuable player again. You should not be surprised Peyton Manning is having success, but no one should pretend they knew he would adjust this well this quickly in Denver. Quick turnaround for the Indianapolis Colts Directly related to Peyton Manning's comeback, the other side of the story is what has become of the Indianapolis Colts after the face of their franchise's dramatic departure to Denver. Well, insert Andrew Luck as the new face, and stunningly the Colts have the same record as Denver (5-3), and with a rookie quarterback who has thrown for exactly the same number of yards (2,404) as Manning this season. The Colts are a Thursday-night win in Jacksonville away from going to 6-3, which not even the most biased of fans could have predicted for the team in 2012. After a 2-14 season, the Colts cleaned house, replacing GM Bill Polian and coach Jim Caldwell with GM Ryan Grigson and rookie coach Chuck Pagano. Other big names besides Manning were released, and the team did not have the cap room to bring in many high-caliber free agents. The rebuild was expected to take a few seasons. But Colts fans were excited because of the luck they had on their side. With the No. 1 overall pick in the draft, there just so happened to be a highly-touted quarterback prospect available: Stanford's Luck. He has been the real deal, providing the Colts the big-time drives late in the game they sorely missed in 2011 when they were 1-7 at fourth-quarter comeback opportunities. Luck has already led four game-winning drives in his first eight games, which no other rookie quarterback in NFL history has ever accomplished. He led an 18-point comeback in the second half against Green Bay, and passed for a rookie record 433 yards against Miami in a battle of 4-3 teams in Week 9. Luck converted 12 out of 17 third-down plays in a stunning performance against a Miami defense that led the league in third-down defense coming into the game. With plenty of records and accolades to come, Luck's season has been nothing short of brilliant so far. But not all luck has been good for the Colts this year, as coach Pagano was diagnosed with leukemia during the team's bye week, moving offensive coordinator Bruce Arians to interim head coach. The emotional punch has been a rallying cry for the underdog Colts as they have ground out their two most impressive wins on days when their coach was nearest to their minds (Green Bay after the diagnosis) and their hearts (Miami with Pagano in attendance). The Colts have needed that "Chuck Strong" mentality, as it has not been an easy path to 5-3 by any means. With just three takeaways on the season, the Colts tie the 2011 Steelers for the fewest takeaways through eight games. Bruce Arians was there in Pittsburgh and learned how to deal with that disadvantage last season. Registering zero takeaways during this three-game winning streak, the Colts are only the second team in NFL history (1992 San Francisco 49ers) to win three straight games without the benefit of a single takeaway. But timely clutch play from Luck and the defense has led to this 5-3 start, which is big in an AFC not at its best this season. The Colts are 4-1 under Arians, getting better every week, and they provide us with this season's underdog you love to root for. Fab Five: Rookie quarterbacks continue to shine You knew it was going to be an experiment with an unprecedented five rookie quarterbacks starting in Week 1, but Andrew Luck, Robert Griffin III, Ryan Tannehill, Brandon Weeden and Russell Wilson have continued to show enough progress to keep their jobs, and most are thriving halfway through the season. Sunday's marquee showdown between Luck and Tannehill was historic in many ways. Assuming both have long-term success, it will be looked back on as a classic first meeting between the two in the AFC, and with historic results. It was the first time rookie quarterbacks with winning records met this late in the season. We knew that going on. Coming out, the game produced the most prolific rookie quarterback duel in NFL history. Luck had the record 433 yards, and Tannehill answered with 290 yards for a grand total of 723 passing yards. What was the previous high? Try 592 yards in a 1987 replacement game between Ed Rubbert (Redskins) and Shawn Halloran (Cardinals). Wow. They sure do not make rookie quarterbacks like they used to. The 2012 rookie class has produced nine individual games of 300 or more yards passing, which is already the most by any rookie class in NFL history. Luck has had four of the games, tying Peyton Manning (1998) for the record. Luck is on pace for a staggering 4,808 yards passing. Robert Griffin III is trying to become the third rookie quarterback ever with a passer rating over 90.0 (he is at 93.9). Russell Wilson has 13 touchdown passes, an 87.2 passer rating, and has led Seattle to a 5-4 record. Like Luck, Tannehill has already passed for over 430 yards in a game this season, and he has not thrown an interception in his last four games. Weeden is the oddity in that he's 29 years old, but he has thrown for two touchdowns in four games, and has three games with a passer rating over 90.0. Despite their 2-7 record, Cleveland's been competitive all season. The 2012 rookie quarterback class is on pace for the most starts, wins, passes, completions, yards, and touchdowns in NFL history by any rookie class. While it is true that it may never be easier to adapt to the NFL out of college than right now, the reason for that is the players are much more seasoned and ready for the move. Rookies starting and producing immediately will become the norm. Saints sinking without Sean Payton Clearly this was going to be a difficult season for the New Orleans Saints with the season-long suspension of coach Sean Payton, and suspension for interim coach Joe Vitt who only just returned last week. But most still believed Drew Brees, the NFL's highest-paid player, was going to be able to lead the team to a winning record and the playoffs. The offense has been spotty, including one of the very worst performances of the Brees era in Denver in Week 8. But Brees is still putting up decent numbers with 22 touchdown passes in eight games. He is still on pace for 5,098 passing yards. But even with some of the early-season turnovers, ignorance of the running game, and general inconsistencies, hardly any offense could pick up the slack for this defense, which ranks 30th in points per drive allowed (2.56) and dead last in yards allowed (41.07 per drive). The Saints are the first defense in NFL history to allow at least 400 yards in each of their first seven games. The minimum has been 421, and three times they have allowed over 500 yards. Starting 0-3 was a real catastrophe, especially when you consider the opponents: Washington (3-6), Carolina (2-6) and Kansas City (1-7). Each team won their first game of the season against New Orleans. Carolina's only other win is over Washington. Worse, the Chiefs have not led in regulation once this season, but beat the Saints in overtime after coming back from a 24-6 deficit in the second half in New Orleans. The season has been a mess at 3-5, and with so much talent on offense, high draft picks on defense, and many of the coaches retained from Payton's staff, the Saints have been the most disappointing team of 2012. With two games remaining against undefeated Atlanta, and tough matchups with the Giants and 49ers, it may only get worse for the Saints as they look to host the Super Bowl in a season they have virtually no shot of making the postseason for. Doug Martin: Do not forget the factor back He was the second running back taken in the 2012 draft, but Boise State's Doug Martin was 28 spots behind Alabama's Trent Richardson, who went No. 3 to Cleveland, when the Tampa Bay Buccaneers chose to pair him up with LeGarrette Blount. Remember when Blount said in August that he and Martin could be the best pair of backs in the league? Well, maybe Blount was right, but it's mostly been Martin playing the role of Batman to Blount's Burt Ward-like portrayal of Robin with his 121 rushing yards this season. Anymore, 121 yards for Martin sounds like a good half. After a solid-but-subtle start to the season, the rookie sensation has exploded the last two weeks, producing 486 yards from scrimmage and six touchdowns in wins over Minnesota and Oakland. The 486 yards from scrimmage are the most for a rookie running back in consecutive games in NFL history. Martin, coming home to Oakland, rushed for a team-record 251 yards and four touchdowns on Sunday. That was even after losing 14 yards on his final three carries to kill the clock. The only other player to ever hit those totals (251 rushing yards, four touchdowns) was Denver's Mike Anderson (also a rookie with the exact same stats) against the Saints on December 3, 2000. Martin scored on touchdown runs of 45, 67 and 70 yards, becoming the first player in NFL history to score three touchdown runs of 45 or more yards in the same game. The only other player to have three scoring runs in one game of at least 30 yards was Adrian Peterson in 2007. It was an incredible performance that came after Martin had 214 yards from scrimmage in Minnesota in Week 8, including a 64-yard touchdown reception. Martin joins Billy Sims (1980), Eric Dickerson (1983), and Mike Anderson (2000) as the only rookies to have consecutive games with more than 200 yards from scrimmage. Martin's seven touchdown runs rank second in the league, he has yet to fumble on 174 touches, and is the season's third leading rusher with 794 yards. No disrespect to Trent Richardson (575 yards, 5 TD in Cleveland), but once again we see that a team can find an explosive running back without using a very high pick in the draft. The 31st pick is still relatively high, but if you can get a stud skill player for a cheap initial contract, then it's well worth it. There is also the funny coincidence that Blount would lose his job to a Boise State player given his past, but at least he respects the skills of Doug Martin. Now every defense will be sure to do the same when playing the surging Buccaneers (4-4).