"I think part of it is [Utley's] inability to keep his leg strong during the course of this time," Amaro said. "He wasn't able to do as many things with his legs, which is probably the most important part of hitting, strength-wise. I think that has something to do with it. But he's still a very dangerous hitter. I think he's a great hitter. He wasn't producing with the power he has. I think it has something to do with the strength of his lower half."
Utley, who went 3-for-5 with three runs against the Cardinals, opened the season on the disabled list because of tendinitis in his right knee. There was a chance he could have missed the season. He returned to the lineup, but he hit just .259 with 11 home runs and 44 RBIs in 454 regular-season at-bats.
Utley's .769 on-base plus slugging percentage was his lowest since his rookie season in 2003, when he had a .696 OPS while playing in 43 games. Utley's OPS from 2005-09 never dipped below .905. It was .832 last season.
Amaro said he thinks Utley can improve his strength going forward. He said it's not a matter of Utley being too beaten up or suffering too much pain to be an effective offensive player.
"He hasn't complained about any pain or discomfort," Amaro said.