Ritz is probably the best US distance runner to never break 4 in the mile. I thought he'd be too old at this point, but after watching those Citius Mag videos, I'm changing my mind. I'm not sure how fast he was going, but I think he was hitting sub-5 pace while yelling words of encouragement, wearing jeans, and hardly breaking a sweat all at altitude.
He's got a monster base built up from 20 years of high mileage, and he's recovered by spending the past few years doing 20 mile bike rides alongside Joe Klecker at altitude (and presumably chasing his athletes around the track). He was never much of a speedster, but he just has to be fast enough to run 59s for 4 minutes.
He's also in the perfect position, seeing as he meets with the best miler group in the world 6 days a week. With the base he has, 15mpw of fast paced stuff should get him there in no time (in my expert opinion). I will call him the GOAT if he does it.