INDIANAPOLIS -- Justin Gilbert's troubled rookie season might run deeper than a lack of maturity and punctuality.

Browns coach Mike Pettine said the young cornerback, who drew criticism from teammates and coaches alike, has been dealing with a "very personal" issue that came to the team's attention at some point before the season ended.

The coach would not reveal the nature of Gilbert's problem, but it's the first time he's mentioned it to reporters.

Pettine was asked if he had a better handle on what led to the 23-year-old's struggles both on and off the field. Was it a poor attitude and lack of professionalism?

"It's more than that," the coach said. "I don't want to get into it. It's very personal and I'm not going to get into details about it."

Pettine and Gilbert met before the player left the Cleveland-area for the off-season. The coach said he was aware of the cornerback's personal problem prior to their chat, but not before the Browns selected him with the eighth pick of the first round last spring. Pettine did not specify when he became aware of it.

Gilbert and Johnny Manziel, the 22nd overall pick, were called out by teammates late in the season for off-field transgressions such as showing up late for meetings and functions. Gilbert was suspended for the final game for such tardiness.

It was an embarrassing ending to a season that began with him getting beat repeatedly in the opener against the Steelers and saw him lose playing time in favor of undrafted K'Waun Williams and fourth-rounder Pierre Desir.

Defensive team leaders Karlos Dansby and Donte Whitner characterized Gilbert's year as a "wasted season."

Prior to the season finale, the Oklahoma State product vowed to change and that he would be "great."

"I'm not mad at anyone about it, I brought it upon myself and I can take that and roll with it," he said. "I messed up, but I can promise my teammates I'm going to make it right ...

"I've just got to come back next season and turn it all around. ... I can assure everyone here that I will work a lot harder, in the off-season and during the season. That's one promise I can make."

Although lumped together for their first-round draft status and forgettable seasons, Gilbert and Manziel are different people. The cornerback is quiet around the media and doesn't seek the limelight. Early in the season, Whitner seemed to be challenging him, trying to draw him out.

Gilbert played sparingly yet flashed his potential, including a pick six against the Colts. Many agree the defensive back doesn't lack for talent.

It's a matter of resolving his "personal" issues and living up to his vow of being more accountable.

"I had a good meeting with (Gilbert) before he got out of town," the coach said. "It was very positive, but it's similar to what I said about Manziel before the end of the year -- words are one thing, actions are another. (Gilbert) was very resolute that he was going to go and get things right."