IT'S ALWAYS a telling campaign moment, a candidate's official entry into a race. Four major figures have made the political plunge in recent days. The results: an awkward crash, two entries that were decidedly slapdash, and one pretty impressive splash. Worst first. That would be Treasurer Tim Cahill, declaring his independent gubernatorial candidacy at the Omni Parker House. Up soared Tim for Governor on ambition's soaring arc. Then came an expedient fiscal tuck and an implausible economic twist - a call for lower taxes, with the suggestion lower rates will reap sufficient revenues to fund state government. Add a plodding style, an inflated self-image, and a text dropped and fumbled with mid-speech, and the result was a belly flop painful enough to make one wince. Give Cahill a D, as in Dreadful. Attorney General Martha Coakley mustered an enthusiastic crowd to the Parker House for her US Senate announcement, but if the audience was lively, the candidate herself proved underwhelming. Urgency drove her decision to run, Coakley declared. That urgent cause? 'I have decided to run for the Senate because I believe government has to work well and work for everyone.' Not content with that daring dose of rhetorical adrenaline, Coakley revisited her making-government-work theme twice more in her short speech. In between, she offered a tour of her girlhood, reviewing the values her parents taught her - the importance of family and community, of pitching in, of planning for the future, and of making government work (ah, just kidding on that last one ) - and recalling her first job, scooping ice cream at Howard Johnson's. But for those hungry for a scoop of senatorial substance, a general declaration that Coakley wanted to 'get results' on health care reform, the environment, public safety, and civil rights was about as specific as it got. Give this vague, cautious, uninspired front-runner's speech a C. Celtics co-owner and Bain venture capitalist Steve Pagliuca at least announced in a different location: that big and oft-renamed sports box where the Celtics and Bruins play. But Pags, who summoned up a roster of well-tailored Bainiacs as his convenient cult-like claque, didn't seem to have any better idea than Coakley why he should be in the Senate. His value-add, as consultant types say, is his business experience, which, he declared, 'has given me a firsthand perspective on how to get our economy and country back on track.' So, how? Sadly, Pags proved as much of a tease as those ads that promise a surefire way to gain a fortune or lose your love handles, all before Tuesday. 'I believe in a team approach - that business, unions, and the government must solve problems together, not apart,' said he. (The Celtics co-owner, the Celtics, a team, the team approach - get it?) That left me wondering just how carefully old Money Pags has been paying attention to public affairs as he's gone about accumulating his glittering mountain of gold. Still, a decent Q&A session, including a halfway interesting answer about financial re-regulation, boosted this otherwise nervous, nebulous, nerdy entry up to a gentleman's C. In sharp contrast, attendees at US Representative Michael Capuano's Senate announcement at (you guessed it) the Parker House were treated to a witty and pointed performance. Unfortunately for Capuano, that came from US Representative Barney Frank, who testified both to Capuano's political ability and the value of his Washington experience. But Capuano gave a shrewd speech, too, portraying himself as a liberal fighter in the Ted Kennedy tradition, a claim he buttressed by citing his votes and voice against the Iraq war and the Patriot Act as well as his consistent support for a robust public health care option. In the Q&A, Capuano contrasted his outspokenness with Coakley's caution, while Frank aimed a deft dart at Pagliuca, quipping that 'it's important for people to think outside the box, but you gotta know what the box looks like.' To be sure, this wasn't a stunningly graceful dive - more like a Capuanian cannonball. Still, his forceful, attention-getting B-plus event made it clear Capuano is a candidate to be reckoned with. Scot Lehigh can be reached at lehigh@globe.com. 