It's cool when things work out for players you like and equally disappointing when players you thought had something don't work out. Onwenu for me so far is more than I ever thought he would be and I really liked him. He's an interesting case study.
I wish I had more conviction with his grade. I did OL close to last because I was still reading different books on OL technique. What is the proper foot, arm, hand, leg, hip, back, etc. positions for a cutoff block, a reach block, a drive block, combo blocks, etc. Having never played football learning the intricacies of each position requires a lot of study. When I was watching Onwenu I was confused why he was considered a later day 3 guy. I was watching his technique and ability his last year and thinking "OK Limberakis, what the fuck am I missing here because *checks books* he's doing almost everything right... this must be because I am not a seasoned evaluator. There has to be something I am missing. Is it just because he's huge/too-big? But even for a big guy he's playing nimbly in zone and gets to the second level - his size only showed up when he missed a few LBs during gap pulls. OK, so his lack of quickness does show up from time to time and there are not any guys who really play at his weight, so let's be conservative, note his power, success, and technique and give him a lower but still draftable grade." In the end I didn't let my OL grades go above or below guard-rails I made for myself based on 6-7 talent evaluators who are prominent and respected in the draft community. That's why I gave him a 5.99 which is roughly a 6th round grade even though I liked him a lot more than his grade would indicate. These past 4-5 months I've read somewhere around 8 more football books including two just on OL. I would recommend: Complete Offensive Line by OL Coach Rick Trickett. Rick Trickett and Dante are friends. Rick is highly respected in New England. The other one is a book that has video clips you can then access online for examples: Building The Block by 2 time pro-bowler Le'Charles Bentley who now runs an OL academy.
In retrospect knowing what I do now about techniques and responsibilities I would have give him somewhere in the range of 6.5 to 6.99 with the caveat that he needed to play at a lower weight*. That's a roughly 4th round to 5th round grade if you want to try and translate it (so I would have bumped him up a round or two). His performance and technique were very solid and his power was outstanding. But even with that in mind... I wouldn't have guessed he could play RT - I figured he was either going to be an addition to their goal line or jumbo packages and/or a guard. I still want to see him challenged by a faster pass rusher.
*It was impossible to know that a trimmed down Onwenu was going to move like a guy who weighs 30 pounds lighter than he is now. I mean look how fluid he is vs his Michigan tape - he can get to the second level on outside zone plays even quicker, make cutoff blocks to LBs easier, it's really phenomenal stuff vs him whiffing sometimes on LBs when he pulled back in 2019. He has much better body control when he is in space now even though it was adequate with Michigan (keep in mind though that was against college players). This reminds me of what Bentley says in his book about body composition (one of the five pillars of offensive linemen). Basically you want to focus on your ability to execute and that additional size can impact your mobility without increasing your strength so instead of trying to be a certain weight play at the weight where you are most effective at your job. If that is 290 pounds vs 300 then play at 290. If you played at 375 like Onwenu did but you would be even more effective because of mobility gains at 340-350 then by all means play at 340-350. If the NFL knew that Onwenu would be this kind of athlete at 340 and he could stay and keep in shape at that weight obviously he would not have gone in the 6th round. But there was really no way to know that.
One last note. Lance Zierlein had a theory he talked with Dane Bruglar that for guys in the back of the draft one of the things to do is to take a gamble on someone with an elite trait. Now I am not saying Lance is right or wrong on this philosophy (because there are other types of players you take gambles on like people who profile as elite STers) but for Onwenu he certainly had an elite trait: power.