Oh I have a theory about this as well *grins* that it's not that Clint doesn't have the skills but how he uses them. Bad choices, like jumping off buildings. (No Clint, the car wasn't meant to fit down that alley. No Clint, sunroofs aren't for shooting arrows out of. No Clint, driving it off a cliff was a bad idea.) But then Loki took over and BAM no more choices. Just the skills and Loki utilising them. (Yet another reason why Maria was pissed: no Clint, you can't just take the alien and escape by outdriving me.)