I still can't figure out why he was a free agent for over 3 weeks.
Unless it had something to do with his shoulder, IDK either. After performing very well for 9 games as a rotational 3-4 OLB, the Colts put him on IR at the beginning of last December for a should injury, so maybe it's a chronic thing with him? OTOH, the Colts switched from the 3-4 to a 4-3 this season, and let some good 3-4 players go (e.g., Hankins in March).
League-wide, the balanced has shifted significantly from a majority of 3-4 defenses to a majority of teams fielding variations on the 4-3. So there have been a lot of veteran 3-4 type players looking for work for extended periods.
For example, it was the Browns' switch to the 4-3 that made Shelton expendable, and it appears that the Cards shift to a 4-3 may have left Bucannon without a spot in their lineup.
While the Pats are superficially a "4-3", they use a sometimes complicated mix of 3-man and 4-man fronts that incorporate both 2-gap and 1-gap principles, sometimes in the same front.
Back in 2009-2010, BB began moving away from a more or less pure 3-4 because, as he himself said, quality players suitable for a 3-4 were become more difficult to acquire as more and more teams had shifted to a 3-4 between about 2005 and 2007. One might think that there's a surplus of 3-4 types to be had now, but I don't think that many colleges are using it, so a shift back to the 3-4 probably isn't in the Pats future.
