The moment the Detroit Lions traded for defensive tackle Damon Harrison Sr. last year, it transformed their defense.
From Week 8 on, the Lions held opponents to under 65 rushing yards in five games, tied for the NFL high. They only allowed 3.76 yards per rush, the second lowest in the NFC in that span. They only allowed 925 rushing yards, the fourth fewest in the NFC in that span.
But it hasn't materialized that way through seven weeks.
Detroit's rushing defense ranks 29th (139.2). They're allowing 4.9 yards per attempt, which also ranks 29th. The defense as a whole ranks 31st (428.7), and the Lions are coming off a game Sunday where they allowed 503 total yards in a loss to the Vikings and 166 yards on the ground.
Harrison said Monday the problems the Lions are having upfront start with him.
"I have to do a better job in the middle and getting some of those plays I'm used to making that I'm not making this year," he said. "It's a lot of things I can blame it on, but the only thing I can do at the end of the day is just throw effort at it during the practice week and try to perform on Sunday."
Harrison led all defensive tackles last season with 81 tackles. He was a force in the middle, and one of the best run stuffers in the league. This year, through six games, he has just 15 tackles.
He was ranked as the No. 1 run-stopping defensive tackle the last six years by Pro Football Focus. This year he's currently 47th.
So why hasn't Harrison been as effective?
"I don't know," he said. "It's a lot of things I can put it on, but again, I'm not here for that. I'm just trying to correct it."
Harrison held out in the spring for a new contract and missed most of training camp.
He said missing all that time in the preseason could be playing a factor, but he also said he's played a lot of football in his career, and that it shouldn't be a factor.
"I just have to get better and get better fast," he said. "Let's just say teams are doing a good job of making sure I'm accounted for. It hasn't stopped me in the past, and I don't see why it should stop me now."
Harrison has been neutralized for the most part through six games, and Detroit's run defense has suffered for it. Harrison said teams are doing a good job getting him on some things he's struggling with right now, though he declined to offer up what those things are.
His frustration with his play so far was evident Monday.
"Especially when my entire career (stopping the run) has been the only thing I've been known for," he said. "To see the numbers where they are now is disappointing."
He did say, however, that he expects things will turn around for both him individually and this defensive line as a group.
"It has to," he said. "It has to. There's no other way. It has to. We just have to get it done and it starts with me."