As pointed out, he graduated during the 2019 season. Baseball America had him as their 11th ranked prospect in 2018 and 8th in 2019. I had him 14th heading into 2019. Most reports had him as a near MLB ready back end starter (with noted good defense). He then added a little velocity and just got incrementally better across the board. This year he has totally changed up his pitch mix, dropping his slider for a curveball and adding a cutter. There were some who really like him, he did hit like his 99th percentile outcome, but like a 75th percentile, above projection, but not above what people thought was possible.
In the Spring of 2021 generally there was bemoaning that he missed 2020 due to COVID he couldn't test negative for, and that had he been in the bullpen they would have probably made the playoffs. I think there was generally more sentiment at the time he was trending towards good multi inning reliever, but then he was better than that and carried the velocity and other gains into the rotation.
Prospect lists miss on guys all the time, I would say when it came to Ranger they generally have been there along his strange journey adapting with the changes.
He was a fringe prospect back prior to the 2017 season because he was like 88-93 and during his disgusting 2014 in the VSL he was 85-87.