5 Thoughts From the Champions League The group stage of the Champions League is almost complete. One more round of matches remains in December for teams to sink or swim and reach the knockout stage. Here are five thoughts to chew on from this week's fifth round of group games: MATA DOESN'T MATTER: The sight of Juan Mata bundled up against the November cold on Chelsea's bench yet again was like seeing a racing car that never leaves its garage: impossible to look at without thinking, "What a waste." Coach Jose Mourinho's infrequent use of Chelsea's 2012 and 2013 player of the year is increasingly baffling. After the 2012 Champions League winners sleep-walked through a 1-0 defeat at Basel in Group E, Mourinho rightly observed that his team looked tired and mused that he perhaps should have used fresher players. Well, they don't come much fresher than Mata. Tuesday night marked the eighth game this season that the Spain international, such a fine servant for Chelsea since he joined in 2011, sat unused on Mourinho's bench. Of Chelsea's 20 games under Mourinho in the manager's second spell at the club, the midfielder has started in just eight. For only two of those did he play 90 minutes - both League Cup wins of lesser importance, against third-tier Swindon Town and a second-string Arsenal side. Mata also came on as a substitute in three additional games. Mourinho prefers Eden Hazard on the left wing and Oscar in midfield where Mata has been effective in the past, with darting runs and incisive passing. The thin excuse Mourinho uses is that although Mata "deserves to play," he only has space for 11 players in his starting team. In short, Mata would be better off at a different club that could use him. There should be no shortage of those for a player of such worth and still only 25. That big clubs rotate players is understandable. But leaving out Mata when Chelsea needed inspiration and fresh legs was not. A waste. ALL GUNS FIRING: One reason Arsenal looks so good this season is that goals can come from almost anywhere in Arsene Wenger's team. An array of 13 different players has built up the Premier League leader's total of 38 goals in 21 games. The bulk have come from striker Olivier Giroud, with 10, and inspired midfielder Aaron Ramsey, with 11. But others are making important contributions. With both goals in Arsenal's 2-0 victory over a disinterested Marseille side in Group F, Jack Wilshere took his season total to four. The first after just 29 seconds, lofted ever so delicately over Marseille goalkeeper and captain Steve Mandanda, suggested there is plenty more scoring to come from the 21-year-old who says he has learned to relax in front of goal. The England international is now nearly half way to the target of 10 goals he set himself this season. Before, he rushed a little bit. He's starting to think, 'What Ramsey can do, I can do as well,'" Wenger said. Wenger can also expect more goals from Theo Walcott and Lukas Podolski as the forwards recover from injuries. Midfielder Mesut Ozil has scored three. Still, Arsenal looks vulnerable without a decent second striker to back up Giroud. Should the France international suffer a long-term injury, can a coalition of his teammates chip in sufficient goals to win Arsenal its first trophy since 2005? Doubtful. BAYERN RECORD: In setting one Champions League record, Bayern Munich looked increasingly capable of setting another.