According to the F/+ rankings over at Football Study Hall, the 2010 Connecticut Huskies were the worst BCS team over the past six years (limited to six seasons because of lack of play-by-play data before then).
Connecticut ranked 55th overall in 2010. Only three times did a BCS participant not rank in the top 25 for that particular season. The Huskies in 2010 were the worst of those teams and were joined by 2006 Wake Forest (32nd) and 2007 Hawaii (48th). Those teams had the 341st, 190th and 267th best seasons of the last six seasons, respectively.
Here's how the other Big East BCS participants ranked over that period of time (out of 58 teams):
19: Louisville, 2006
23: West Virginia, 2007
45: West Virginia, 2005
47: Cincinnati, 2009
53: Cincinnati, 2008
Guess which BCS conference had two teams ranked in the bottom five over the last six seasons? If you said the ACC, you are correct. And, if you had to guess which BCS conference had the most teams in the bottom ten over that same time period? Answer: still the ACC with four out of the bottom ten: 2005 Florida State, 2006 Wake Forest, 2008 Virginia Tech and 2009 Georgia Tech. It's fun to pick at the ACC over these rankings, but also consider the following:
The general meme is that the Big East (or, sometimes, ACC) steals BCS bowl bids away from strong mid-major teams, but while TONS of teams are better than 2010 UConn, really only a few great non-BCS conference squads have been on the outside looking in -- 2010 Boise State, 2008 TCU, 2006 BYU.
Here's the Big East teams in the Top 20 which did not make the BCS:
7: West Virginia, 2006 (7th in 2006, 34th best season of the last six years)
15: Rutgers, 2006 (9th in 2006, 52nd best season of the last six years)
It gets better for the Big East soon. Here's how future participant TCU ranked over the past six seasons:
13: 2009 TCU (3rd best in 2009, 15th best season of the last six years)
25: 2010 TCU (6th best in 2010, 29th best season of the last six years)
TCU also had the 5th best team to miss the BCS in 2008 (6th best in 2008, 30th best season of the last six years).