I suspect and speculate the train of events were:
1. Draft - OTA
Penny had a lot of success in college,
He surveyed his competitors of Carson, a 7th rounder that was 'injury prone'. Davis, a castoff from 9ers. Both sounded underwhelming. Penny assumed that he was going to be the savior for Hawks' running game if not offense.
Penny was complacent, enjoy $ from his rookie contact, and guess what, didn't train hard and got heavy.
2. OTA
Penny couldn't measure up to Carson, in turns of conditioning. Coaches started pushing him, but that savior assumption persisted. OTA was OTA, come training camp? let me show Pete and Carson, he assumed.
3. TC
Penny still couldn't measure up to Carson and Davis, then his fingers got broken, which ended this TC early.
Slow turn around in his savior mentality, but still guessing he will out perform Carson and Davis come game time.
4. PS
Didn't have much of a preseason due to injury.
5. Season
Frustration started! Lack of achievement led to less playing time follow with negative press. Witnessing Carson and Davis' success, Penny ought be a bit scared by now,
SO yes, Pete is right. Penny's frustration could be VERY GOOD, if Penny is mentally tough and competitive. By now, his post draft savior mentality out to be total gone. If he can leverage his frustration into working super hard, he might, just might be lift the Hawks to a different level.