While enticing, the theory conspiracy fails on several counts I think.
1. The Eagles have a history of failure in big games, playing with a lack of urgency, etc. Look at the last several NFC championships. It seems like they expect superior talent to carry them through, and when they need a late drive they come up short.
2. As noted, McNabb's accuracy problems.
3. The MO of the Patriots, more than anything else, is to play mistake-free football and let the other team beat themselves. That happened again yesterday.
4. It wasn't just McNabb and Reid lolly-gagging, it was most of the offensive team. I have a hard time believing they were all paid off. A conspiracy needs to be kept small, and it's not like you can point to one individual play that was a turning point, so multiple players would have to be involved.