I took over a team this season, and I thought this guy was my most promising pitcher:

http://whatifsports.com/HBD/Pages/Popups/PlayerProfile.aspx?pid=5515094

I didn't think he'd be an ace, but I was expecting a decent mid-rotation type pitcher. Ctrl over 80, splits around 70, pitches of 85,76,67, and 93 velocity and grounder rate. My team is slightly above average in the league for + and - plays, and my park is a slight pitchers park. I'd chalk this up to small sample size, but this guy has thrown almost 300 ML innings.

Is there a rating that is ruining him that I haven't noticed? Or should I expect him to improve?

Thanks.

Interesting.  I think he'll improve.  Although I'll say only having 3 pitches might hurt him a little more than one would think.

He'll do better but 3 pitch starters can be frustrating.    Not sure why. 

Interesting. I didn't know that about 3 pitch starters. Thanks for the information.
Follow up question:
Would it be better to have a 4th pitch that is terrible, like 30 or 40, or not have a 4th pitch at all?

I once thought the threshold was 30 but I saw a DITR got an upgrade that decreased his 4th(maybe 5th) pitch from upper 30s to mid 30s.   That seems to indicate he was dropping it.    So you'd think it's over 40.   Then I get Hardball Dynasty – Fantasy Baseball Sim Games - Player Profile: Andres Jimenez with his weak control and borderline 3rd/4th pitches getting lots of people out over multiple seasons.    So now I'm back to thinking 30 and that the DITR engine doesn't work so well with the dropping of pitches. 

Hardball Dynasty – Fantasy Baseball Sim Games - Player Profile: Robert Olson is a 3 pitch(with sub 40 3rd) guy who largely does well but moves in/out of the rotation due to inconsistency. 

Drop his pitch count a lot.  I'd set him at 75/80; he's probably got a lot of in-game fatigue.

ERA should recover to low-to-mid 4s in PAW AL, assuming your infield defense is average (OK, I checked, it's a pretty average infield defense).

Really? 75-80 pitch count? I read somewhere that the target pitch count should be about 1.3 times Stamina. Rhodes has a stamina of 72, so that would put him at about 90-95. Is that wrong?

Reducing pitch usually works.  That's why I move guys who are struggling as SP to LR.    I set my LR at 40-50.

I run much shorter pitch counts than most people.  Somebody has to pitch the innings, so for pitchers with 25+ DUR and 70+ ST, I may run them at 1.2 ST, maybe 1.3 if they're at 30 DUR.  But a 23/72 I would run at 75/80.

Going back to Hardball Dynasty – Fantasy Baseball Sim Games - Player Profile: Robert Olson and pitch counts.    I run him at 80/95 as a SP.    He's never really had a "bad" season but you'll notice that he's had 4 seasons where he was a part-time starter.  That's because he struggled as a SP, with the higher PC, and was moved to LR with a 40-60 PC.   And his stats improved.

This is very good information. Thank you. Regarding Rhodes, I looked at his game log, and it doesn't appear that pitch counts are his issue. If he was getting tired, I'd expect him to do fine for 4-5 innings then give up a few runs once he hits 75 pitches or so. That isn't the case, though. His problem is that he tends to follow up 2-3 good starts with an outing where he gets completely shelled. But I will definitely use the lower pitch counts for some of my other pitchers.

The way to avoid "completely shelled" is to up the pull setting.    Instead of giving up 5 in an inning, he'll give up three before the hook comes.