The Tampa Bay Buccaneers had a pretty good run defense last year: Football Outsiders ranked them eighth in the NFL, and they allowed an NFL seventh-ranked 3.9 yards per carry. But it seems that as soon as opposing teams introduced a fullback into the equation, the Bucs suddenly couldn't stop anyone. According to Football Outsiders, they had the 24th-ranked run defense against two backs while their one-back run defense was ranked second in the NFL.
That's a pretty curious gap, but it could easily be explained by the fact that facing a fullback usually means lining up with three linebackers, while facing a single back usually means going to a nickel defense. The Bucs had numerous injuries at linebacker last year, which means that sub-par defenders like Dane Fletcher, Jonathan Casillas and Orie Lemon got a significant amount of playing time -- much of which must have come against two-back sets.
Intriguingly, opposing offenses seem to have been aware of this problem with the Bucs defense: no team in the NFL faced two backs more than the Bucs did last year.
Undoubtedly, teams will try to exploit this weakness this year, too. They may find that to be more difficult, though: the Bucs added Bruce Carter and drafted Kwon Alexander to reinforce the linebacking corps, while also picking up Khaseem Greene of waivers. Hopefully that's enough for the Bucs to stop a fullback.