The O-Line wasn't horrible, Newhouse and Ferentz were horrible, but they only made spot starts all year. TE play was horrible to start the year, TE's block... they aren't only there to catch balls.
They didn't bring Ben Watson in immediately because they spent his money to sign AB. Lacosse and Izzo were both injured to start the year. Izzo came back first and was horrible, Develin also got hurt.
When they brought Watson back, TE play immediately improved, when Lacosse got healthy (bye week) the level of TE play wasn't amazing but like the WR's was adequate to good. You can actually see the improvement in rushing statistics which walk lockstep with personnel upgrades.
First six games: No TE's, beat up O-Line = Sony averaged 3.5 yards per carry.
The final 6 games of the season they got Wynn back (Cowboys game), had two healthy TE's (Watson, Lacosse) and also had Elandon Roberts giving them quality experienced snaps at fullback = Sony averaged 4.3 yards per carry.
Blocking matters, this isn't singles tennis.