Yep, between these QB friendly spread schemes and rules favoring the offense, it's easier than ever for QBs to succeed. That's why you see even average to below average guys put up numbers that would have put them in the hall of fame 30 years ago. If you have a QB who is to year 3 and still sucks despite all those advantages, he probably just sucks.
Allen was already showing flashes of brilliance in his second year and he clearly improved from year 1 to 2, so I'm not listening to that comparison. Tannehill is about the only example in recent years of a guy who sucked for 4-5 years then figured it out, but even he's probably not much more than above average at best.
This year is make or break for Lock. If it doesn't click, it's never going to. And that's on him. Not his coaches or anyone else.