Beck wasn't the phenomenon in college that Jimmer was, but the guy had the potential to be a very solid NFL quarterback if he just started off in the right situation. But he started off in a train wreck of a situation and from there you carry with you the stigma of the train wreck and fight politics of "not my guy" along with other politics at future opportunities. 

An insanely small percentage of people can emerge from a bad situation, get a second chance, and make the most of it. Every year new people are coming in gunning for a very small number of jobs and if you don't start off on the right foot it is very hard to box those people out and carve out a spot. 

You almost need things to go right in your first chance (unless you are extremely lucky or extremely elite) to have a second chance work out. The politics and baggage are just really hard to overcome.

If Beck had gone into a situtation like Tom Brady did, then he could still be playing and doing well. I'm not saying he'd be Tom Brady. I'm just saying Tom's situation was ideal for getting a solid chance in the league (back someone up on a high functioning team and then replace them with good pieces around you and experience). 

I think if Westphal hadn't been ousted then Jimmer would still be a solid role player in the league. Instead there is too much baggage for him to overcome in the absence of someone taking a crazy risk and making him a key piece for their franchise - which isn't going to happen.

Jimmer needed to be a second round pick and not have a circus follow him. If he'd been a low first round or second round pick with no circus and gone to San Antonio, Dallas, Memphis, Toronto, or some mildly functional organization without the weight of the world on his shoulders he would probably be having a very respectable NBA career. 

If John Beck were coming out last year or this year and could back up Drew Brees through his retirement and then take over or could have been like Rodgers backing up Favre then coming in, I think he might have had a long, productive NFL career. Having the good fortune of going into an ideal situation is more important than most people acknowledge for professional success - other than truly elite outliers.