I've been reading Pat Kirwan's great book 'Keep Your Eye Off The Ball' and while he doesn't mention SpyGate at all, it just further solidifies how the cheating by the Patriots helped give them a HUGE advantage. I think the 'experts' that claim it didn't help were either:
1) Pats fanboys or former Pats players
2) They don't fully understand how the coaching and scouting work in the NFL
3) They are just ignorant.
If you remember, the great thing about the Pats back then was how they 'guessed right' on plays..particularly big plays...all of the time and that they 'didn't have any tendencies.' In today's NFL, it's impossible to 'guess right' that often and not have any clear tendencies.
This is where I agree with guys like Parcells that execution is so important (although I think Parcells goes overboard with that idea). Teams generally have an idea of what's coming and you're not going to fool teams that often, so you need to out-execute them a large part of the time. But there's a difference between 'having an idea of what's coming' and 'knowing exactly what's coming' and that's the difference between being a HC who continually lost in Cleveland and then his first year in NE to becoming a HoF head coach.
Of course, you'll get the 'they went undefeated when they got caught in the first game.' My belief is that the one thing Belichick and Pioli did that was stupendous is use their success to their advantage. We heard about all of this nonsense of 'The Patriot Way' and how the Patriots were a different organization. Well, other franchises bought into this crap as well and hired their coaches (and failed), traded for their players (and failed) signed their free agents to big contracts (and failed). Meanwhile, the Pats were able to get the better end of deals and eventually wound up with Moss (the greatest deep threat of our generation) and Welker (the greatest slot receiver of our generation). By then, Brady developed into a great QB and they could just throw the ball all day and score a billion points. Plus, the refs just happened to be awful that year and give the Pats every break they could. But, notice how the running game stunk that season and the defense was really more or less mediocre. They didn't stockpile those areas with massive talent and no longer had Ernie Adams telling them with the exact playcall was.
I compare it to playing poker with somebody who has been cheating the entire time and then gets caught. But by now they have such a huge stack of chips that they have put themselves in such a favorable position that it makes it difficult for them to lose...but they are nowhere near as good as they were when they were cheating.
YR