On the one hand, you have a 23-year-old rookie putting up a basically league-average ERA with a 12-4 record.
On the other hand, you have a guy who only struck out 100 and who walked 72 in 182 1/3 IP.
That’s the problem here; his peripherals aren’t the peripherals of a pitcher with a 4.00 ERA but of one closer to 5. He can live with the walks, but I don’t think a pitcher can be successful, long-term, with a strikeout rate like that unless he gets lots of ground balls and has a really good defense.
The thing is, Ramirez appears to have wicked stuff, the sort of stuff that should produce strikeouts. But unless he starts getting them (and he never did much in the minors, either) it’s going to be a tough road. The pitcher most-similar to Ramirez (by similarity scores) at age 23 is Kirk Rueter, another lefty who’s been successful with bad peripherals. But that’s a product of two half-seasons for Rueter, which might be instructive. As a rookie, Rueter was a key component of the Expos’ abortive miracle in 1993, going 8-0 with a 2.73 ERA. The next season, he went 7-3… but with an ERA of 5.17, and soon enough was on the road to San Fran. Still, if Ramirez has Rueter’s career he’d probably be thrilled.