He mentioned the Chiefs and Browns who run similar defenses to the Patriots as among the slowest teams in the league, this is not a surprise to me at all. The defensive scheme is going to make for a slower than average team. The Patriots put 3 big DL on the field, and their 2 ends are usually no faster (and often times slower) than the 3 technique of a 4-3 team. So, the Pats give up a lot of speed on the Dline for strength/power. At linebacker, the much discussed Belichick measurables at OLB are very similar to measurable of 4-3 DE's. Teams like Pittsburgh that have a more attacking style 3-4 play much smaller guys on average than the Pats do at this position. Finally, at ILB, the Pats usually will have a player at one of the two spots (usually SILB) that would be too slow to play in a 4-3. That is certainly not currently the case with Mayo/Guyton starting on the inside. On offense, the Patriots have one guy with elite speed in Moss and one guy with very good speed in Maroney. Watson would have fit in to the very good speed category last year as well, but is now gone.
I bet the Patriots were slower in 2007 than they were in 2009, but the leads the offense got allowed the defense to play faster. Think about it: Bruschi, Harrison,Vrabel, and Sanders would all be slower than the guys manning those positions in 2009.
Cliff Notes version of the story (IMHO): Pats will never be one of the faster teams in the league as long as they run their current defensive scheme and display a preference (or at least a willingness) to play veteran players.