Yes. I recall that situation. At the time i chalked it up to conveying out INTENT more so than what he was ultimately capable of playing. I think I had heard/read some commentary at the time about Zack would play initially at guard and then be out long-term answer at RT. So they just stuck with me. It wasn't until I really dove into his draft profile (prompted by Darth's earlier post) that I see the consensus view that he's best suited to play guard as his natural position. I guess we could've used some longer arms on Zack when he tried to get that block on the Murray fumble against Greenbay in the 2014 playoffs, huh??? On the latter, I know the blame for that play typically goes to Murray for not securing the ball adequately (I know that's where I placed it) but i have always wondered to what degree Zack is haunted by that play for not sustaining the block for a split second longer?
Yes, OTs usually have more length (arm length + height). Occassionally they will have short arms but those guys are usually tall (i. e. Joe Thomas has short arms for an OT but he is almost 6'7).
Martin is right at 6-4 with short arms (for an OT). Also his wingspan is small (body width + 2x arm length).
La'el Collins has slightly more height and arm length but a significantly bigger wingspan. He would be closer to being a fit physically than Martin. They both played LT in college.
Having said the above, either Martin or Collins could move to RT this week with no practice and be better than Doug Free.