Not that good or not given a fair shot?

I have watched bits and pieces of some preseason NFL over the last few days (yeah I know but it's football!) and I had a thought about some former UGA QB's that didn't last very long in the NFL. David Greene who was the winningest QB in NCAA history (until Colt McCoy broke his record playing the Little Sisters of the Poor and Baylor) only lasted a few seasons with the Seahawks after being a 4th round pick and then bounced around the league for a couple of years before retiring. DJ Shockley was the #3 for the Falcons for a few years before getting cut in favor of Sarah Jessica John Parker Wilson and his Bama bangs and last time I checked was playing in the Arena League. After watching some truly horrible QB play in the NFL over the past few years (and especially the last few nights....Curtis Painter anyone?) my question to you is: Were Greene and Shockley not that good to begin with or did they not get a fair shot with their respective teams? My take on it is that Greene's arm strength and ability to throw the long ball or deep out was a limiting factor. I also think that somehow he got on Mike Holmgren's bad side at Seattle and was "black listed" so to speak around the league (every thing I have ever heard about Greene over the years says he is a hard worker and a good person so I can't imagine what he could have done to incur the wrath of Holmgren). I always thought of DJ as a poor man's Vince Young (but not batsh!t crazy). Maybe not quite as strong of an arm or as accurate as Young but a serviceable QB to say the least. I feel like he missed a golden opportunity in '08 when Vick was in prison and he blew out his ACL in Buffalo. Maybe it's the homer in me, but I just can't understand how two very successful QB's at a top program in a pro style offense aren't in the league in some sort of capacity now. Especially with guys like Curtis Painter, Tyler Thigpen, Tavaris Jackson, Charlie Whithearst, John Parker Wilson, the two no loads at Arizona that played last year, and Shaun Hill. Really? What say you Dawgsports?