Well, we almost lost Round 1 to Atlanta in 2008 BECAUSE of Doc changing his rotation...Luckily, Ainge or somebody had him change back---and we won....But 2008's Championship was almost blown by him and him alone.
This x 100
And Doc is the reason the Celtics lost game 7 in 2010. He changed his rotation for game 7 and barely played the bench, leaving Nate Robinson on the bench even though they had trouble scoring and scoring was the reason Nate was brought to Boston. He also left Tony Allen on the bench when Ray couldn't hit a shot to save his life. No, Tony couldn't hit a shot, but Tony would do what Tony always does, drive to the basket and draw fouls and make an impact on defense. I really dislike Doc as a coach!
There were so many simple adjustments that he could have done throughout that series that would have put us over the top, but he never made any of them. It's like he was incapable of doing so, and I guess that that's probably the case on a whole. He never changed the offense, either, as our guys got older, and if you want to specifically talk about the 2010 finals, why not Marquis Daniels? Yes, he was injured earlier on, but he was available, iirc, throughout that series, and he could have made a big difference, imo. Even Michael Finley could have helped. Yes, Michael Finley. I know that I'll get a lot of flack for saying that, but he could have won us a game or two in the finals, imo, especially in game 3 after Artest kneed Ray in the thigh, rendering him useless, and yet we fought all the way back against the refs, everything, only to lose by, what, 5-7 points? Really? Doc also never utilized Sheed or even JO correctly, treating them as Perk, offensively. Both guys really perform better when they score, and some players are just like that. It helps them feel that they're a part of the game, and Doc never recognized this. JO at least liked to play the post and could have made a big difference at times, but he never got any shots inside, and yet, when he went to Phoenix and Golden State right afterwards, he looked rejuvenated. I get that the Suns have the best medical staff in the league, but still. Rivers did the same thing with Jason Terry, as well.
All in all, I think that Doc is a master motivator, but a crappy x's and o's guy, not to mention his KC Jones-like attitude in regard to playing younger guys. Look at how well Sheed played with the Knicks in his last year before he had to retire due to injury. In 8-9 fewer minutes per game, at age 38, he rebounded at the same rate and blocked close to his totals in 2009-10, and why was that? Because Woodson understood how to get his head in the game. Any time he was in there, they got him the ball, and good things happened because he always had mismatches. Meanwhile, in 2009-10, Doc refused to make him a focal point of the offense as soon as he checked even when he was being guarded by Lamar Odom and Luke Walton.

Luke Walton! Are you freakin' kidding me? Ugh.
The only thing Doc did that was really impressive to me was his limiting of minutes in 09-10. It's hard to do that, but he did it, and we got all the way to the brink of a title because of it, in addition to other factors. The same strategy should have been applied in the subsequent years, imo, but they wanted homecourt after 'losing' game 7, which is perfectly understandable, but is also more of a knee jerk reaction, and we suffered in the playoffs because the older guys, particularly KG, had played more minutes during said campaign. He also might have been hurt, but he wore down in that series against Miami, which likely never would have happened if Doc had kept the big picture in mind. Sigh.