Not sure this is completely fair to Romero. In 2017 he gave up 4 HR in Lakewood and Clearwater. Lakewood suppresses home runs but Clearwater does not. Then in 2018 he gave up 13 HR in 106.2 IP in Reading. He actually gave up more home runs on the road so it was clearly the better hitters in AA and not the Reading park. But he also got better throughout the season. He gave up 11 HRs in his 10 starts in April and May. Then only 2 more in his 8 starts the rest of the season.
No argument that his 3.5/9 walk rate needs to come down. But it does look like he did a better job of keeping the ball in the park in the second half of the season which is the type of development curve one should expect. I think he has earned the promotion to AAA (though injuries did rob him of 30-40 AA innings), but home runs are not my biggest concern.
He does look like a back end 4/5 starter developmentally, but there is really nothing that suggests he could not become as good as Eickhoff or Eflin for instance. Probably needs a whole year, maybe a year and a half in AAA, but I feel better about his stuff than Suarez for instance. Not a world of difference, but if he is throwing in the 92-94 range with a good change and athleticism it is a decent set of tools to work with.