We're getting into the thick of last season's freshmen, as many as 6 of whom would end up being slotted on the OL. McDonald is possibly the least hyped of the 6. Still, he was a consensus 3-star recruit. His biggest weakness, from a recruiting standpoint, may have been his home state. There simply isn't much FBS talent in the state of Massachusetts, so they tend to get overlooked.
But McDonald is a player. He was named to just about every all-star team and award list that he was eligible for in High School. And as a 6'5" 275 pound incoming freshman, he was physically ready to go. The Hoos didn't really have a need at OG (and still don't), so he didn't need to play. Also, he hadn't faced the level of opponent that he would be facing week in and week out in the ACC, so he needed some seasoning. For sure, a season in a college weight program would help him build his lower body strength.
His best attribute coming out of HS was pass blocking. He's got good upper body strength and because he's so athletic, his footwork is fantastic. But he doesn't have the raw strength for run blocking right now. He's better as a pulling lineman than he is in-line firing out on a defender. But that kind of thing comes with practice and better strength.
His frame was (and still is) capable of holding more weight. He's up to 295 already, and will probably get up to 310 or so by the time his UVA career is over. McDonald may play this year, simply because there isn't a ton of depth on the OL (especially due to injuries). At the very least, he'll probably see time on special teams. His athleticism could play well on a punt coverage unit, where he's a good enough blocker to stay in-line and yet quick enough to get downfield and potentially make a tackle.
Coming out of the spring, he was the 2nd string RG, and he very likely remains in that spot right now. However, he is unlikely to be the first OG off the bench in case of an injury to Ross Burbank. Most likely, one of Cody Wallace or Connor Davis would slide to RG, with players moving around at other positions. This is mostly because McDonald simply isn't ready. By next season, though, McDonald may be in line to start at one of the OG spots.