The reason the Lions were almost at the bottom of the list is because they had 77 plays during 2010 where a broken tackle occurred. In all, they were on the field for 996 plays defensively, resulting in 7.7 percent of their plays including at least one broken tackle. (The Lions allowed 89 total broken tackles during the 2010 season.) Only the Houston Texans had a worse percentage (8.1), as they had 81 plays out of 998 with at least one broken tackle.
A big reason why the Lions were only better than one team when it came to preventing broken tackles is Alphonso Smith's poor tackling. Out of all the defensive players in the league, nobody had a higher broken tackle rate. Smith made 35 tackles during 2010, but he also gave up 10 broken tackles. This resulted in a rate of 22.2 percent, which is just awful. Dominique Rodgers-Cromartie had the next worst broken tackle rate, and it is almost four percentage points lower than Smith's.
(Via Kevin Seifert)