don't know where you heard he was good but you are completely wrong. He was at best mediocre. Just that the others around him were in some cases worse so he looked better. He has never been worth it.
I got it from a scouting report...
http://thejetsblog.com/bga/bga-scouting-stephen-peterman/
Peterman has been completely healthy over the past two seasons and in 2010, although he was dealing with a foot issue all year, which
[SIZE=+0]affected him badly[/SIZE], he didn’t miss any games. He struggled badly all year though, although he did play well over the last month. In 2011, he had a solid season and was ranked as PFF’s 16th best guard. However, in 2012, although he graded out positively overall, he was down near the bottom of the league in terms of pass protection. Peterman’s best season was probably the 2009 season that was cut short – he ended up ranked 14th despite missing the last seven games and could probably have finished in the top five if he’d stayed healthy and continued to play at the same level.
So my original point was that he has done well in the past but looks like injuries have really affected him. So me being completely wrong is completely wrong, unless of course you know the guy and have good talks over dinner with his coaches.