Not really surprising that Murray is shooting up the boards. Imo he is the best QB prospect in this class. It's kind of ridiculous that there wouldn't even be any discussion who the best QB prospect is if Murray was 1 or 2 inches taller.
At this time during the 2017 draft, Pat Mahomes wasn't considered a consensual 1st round pick, but a mechanically distraught 2nd round prospect at best, based on pure arm talent. When he declared, most well known pundits gave him a 3rd round grade at best. Not a fair comparison, but it just shows you the post-season/pre-draft process is indeed valuable to get a better feeling for QB prospects.
Murray, be it at 5'9 or 5'10, can put himself in the position to deliver passes. Quick feet, feeling the rush and pocket presence are what make Russell Wilson and Drew Brees successful despite being small. Of course Murray won't be able to make some throws from the pocket like Brady or Palmer, but Murray has always been on the smaller side and is already used to find himself the throwing lanes he needs. Again, Russell Wilson has hurt us a lot since he entered the NFL. While I remember some batted passes, more often than not he escaped trouble and made us pay, or threw from different arm angles to avoid defenders.
Murray being ranked low initially is not only because of size, but also because of being the 9th overall MLB draft pick. Nobody, not even Murray himself, could know that he's gonna play himself into 1st round QB territory, let alone 1st overall consideration. Six months ago it would've sounded like a crazy joke. But here we are. Can't fault him for not really knowing which route he wanted to go. Mahomes faced the same question at some point, but was just a 30th or 35th round selection in the MLB draft. So his decision came much easier and earlier. And don't forget that Pat Mahomes Sr. wasn't a QB like Murray's crazy dad, but a longtime MLB pitcher.
I'm not the biggest fan of taking Murray 1st overall. Rosen hasn't got a fair chance yet and Bosa/Quinnen/Allen are legit elite prospects. But the Murray sceptics seem more like haters to me, which is unfair imo. Of course there are question marks, but my money is on Murray to succeed in the NFL. The question isn't whether MB/SK/KK think that Murray will succeed, but if they think Murray will become better than Rosen. If that's the case, you take him 1st overall without regret. If you think there isn't much difference between them or Murray is too much of a risk, then let's enjoy the great defensive player we draft or possibly the bunch of valuable picks we get for #1.