Ezekiel Ansah had a lot to live up to last season, after the Detroit Lions selected him fifth overall out of BYU, and he delivered a rookie-high eight sacks.

But according to ProFootballFocus, Ansah actually struggled against the pass while dominating against the run -- finishing No. 1 among all rookies.

"Ansah proved to be the best amongst the rookies in the running game, perhaps not surprising given some teams' interest in him as an interior player," PFF's Steve Palazzolo wrote. "He was rarely taken out of plays and he showed that he'd be difficult to block early on in his Week 1 matchup with Minnesota Vikings LT Matt Kalil."

But PFF wasn't quite as high on him as a pass-rusher, grading him worse than all of Detroit's other defensive ends -- Willie Young, Devin Taylor and Israel Idonije -- and 27th overall among 4-3 DEs.

"Many (of the sacks) were of the clean-up variety and he was below average providing pressure elsewhere," Palazzolo wrote. "He graded positively as a rusher in only four of his 14 games, with his best effort coming in Week 16 against the New York Giants. He hit a midseason lull that included a -2.6 grade on 35 rushes against left tackle Joe Thomas and the Cleveland Browns before finishing the season were a perfectly average 0.0 grade in his last six games after coming back from injury.

"It was not an embarrassing first season for Ansah by any means, but certainly not as impressive as the nine sacks might indicate." (PFF does not use official stats and counts all snaps of the ball, even penalized plays, hence the sack discrepancy.)

Ansah met his lofty expectations as a rookie, but clearly has room to grow heading into his sophomore campaign. Even more will be expected of him, too, with Young and Idonije gone and Jason Jones rebounding from a season-ending knee injury.

The bottom line?

"Ansah's impressive play against the run gave the Lions one of the league's most stout defensive fronts," Palazzolo wrote. "As a pass rusher, he would probably benefit from some snaps on the interior, but with Ndamukong Suh and Nick Fairley already entrenched on the inside, Ansah will have to expand his pass rushing repertoire in order to build upon a solid rookie season."

Ansah might have to wait a bit before getting to work on his game. He had offseason shoulder surgery and appears to be dealing with a biceps injury as well, which likely will prevent him from being ready for the start of Detroit's offseason program.