I actually watched a lot of Nubbs games last year (many friends are) so I saw a lot of Martinez's play in real time, and in general I will echo the same sentiments.
His o-line was just, god awful, and one thing to keep in mind from a "luck" stand point, Nubbs was exceedingly unlucky. Look it up, they only won 1 big 10 game, but there PF/PA was dead even, which speaks to how many damn close/weird ass games they were in. Martinez can definitely be blamed for many of those issues, but he also cannot be blamed for as many if not more issues as well. Also Nubbs defense was very inconsistent, they could be equally lock down as equally WTF depending on the game and situation.
I tend to echo your overall assessment, I do think he'll have more TOs than 5 ints, but I expect not much more like 7 or 8. Even with his lack of a oline he still can cowboy it up a bit, regardless he's going to be an exciting watch, and his experience and talent combined with having a competent o-line, and better cast of characters around him that will take some pressure off him, with hopefully a better play caller in Klein will mean he should thrive pretty well.
Assume he's healthy, I think he'll throw for about 2500 yards, 18ish TDs, 8 INTs, and more like 400 or 500 yards of rushing (I think he'll get some big scramble plays to booth the overall numbers). I do think he'll rush for like 8ish TDs, he's too good a runner and scrambler to not find a hole if things break down and take something long on the ground.