I don't know the kid at all -- Murray may end up being really special. That being said, it's almost like the pendulum has swung back the wrong way with QB bias - that Mayfield's success in transitioning from OU to the NFL means that Murray -- an even more "undersized" QB -- will do the same. Athletic ability aside, Mayfield was kind of special in 3 ways, all of which help him be successful at the pro level;
1) Exceptionally strong leadership qualities;
2) Extraordinarily hard worker with chip on his shoulder;
3) Started 44 games in college.
I can't say much about 1) and 2) with respect to Murray -- I just don't know. I'm just saying that those are very important qualities for a QB, and should be factored into any Murray/Mayfield comparision or evaluation. 3) is clear -- Murray has exactly 14 college starts, so he is far less experienced than was Mayfield coming out of college.
I'm not saying that Murray won't be great. I'm just saying that those are important issues that have to be considered before projecting how likely it is that Murray can emulate Mayfield's success.
I also think it's important to note that Mayfield is not a great athlete, but he's elite in the cerebral aspects of the game. His board work and recall were absolutely special according to everyone who met with him pre-draft. That was something that we clearly saw in his rookie season as he grasped the offense quickly--becoming a master of it to the point that he felt comfortable working a defense. He also entered the league at 23 as a four-year starter. Those things helped him overcome the size limitations. Drew Brees and Russell Wilson are similar to Baker in this regard.
Murray was great in college and came from the same system. However, as you say, he does not have nearly the same level of experience under his belt. There were also numerous reports out of the combine that his board work was less than impressive, noted by some harsh feedback passed along from Charley Casserly (who I'm not a fan of in terms of his opinions, but he is well-connected).
He's a much better athlete, but it's yet to be determined how the rest translates given his size. How quickly does he pick up an NFL system and adjust to how NFL defenses mush the rush on him, turning him into a pocket passer? What about larger NFL defenders getting pressure in his face? We just don't know until it happens, as much as we try to project.
It will certainly help him if he goes to Arizona given that system is going to be heavy on similar concepts to what he runs now.
It's just not as simple as "a few short quarterbacks have worked now so size doesn't matter." It still comes down to avoiding hits and learning how to manipulate a defense within your offensive scheme, which requires mastery of it. He could get there, but I think it's important to note Baker's age and experience level when he entered the league versus Kyler's.
It's also easier to see from the pocket at 6'05 than 5'10, even if you are mostly looking through throwing lanes.
