Beck I think I have asked before but Lacy is a low 90s on fastball. I'm still learning the advance metrics, but it seems with his k rate, and ground ball rate this could be a kid moving up the rankings list
Yeah I'd be surprised if he isn't basically where Rucker was to start this year. MLB.com had rucker at #20. As far as advanced metrics, the way to look at k/9 is like this. League average this year among starters is 8.26 per 9 though I think typically you're fairly safe going with 8 k/9 being average. K/9 doesn't entirely tell the whole story. Often what you're more interested in is K:BB ratio. BB/9 this year is 3.10. So just from a rule of thumb stand point 8 k/9 and 3 bb/9 or roughly 2.66 k:BB ratio is average.
When talking about prospects I largely don't care about ERA. ERA in the minors is sort of useless because you could be dealing with a guy who's too young for the level or vice versa a guy who dominates younger guys. You can also deal with bad defenders. Strikerouts and walks basically take everything else out of the equation. Typically speaking, the rest is BABIP related anyways. One caveat I'd put in there is HR. Some guys just give up more and that's going to hurt your ERA in ways that are more impactful than any other hit.
In terms of expectations, you first gotta look at age average for levels. DSL which is a rookie league for IFA average is 17.7 for hitters and 18.5 for pitchers. Arizona rookie league which is the cubs rookie league(There's the appilachian rookie league and gulf coast for other teams) is 19.6 years old for hitters this year and 20.5 for pitchers. A- is 21 and 21.4. Midwest league(A) is 21.3 and 21.9. Carolina League(A+) is 22.4 and 23.1. Southern league(AA) is 24 and 24.4. And the PCL(AAA) is 26.6 for both. It's important to keep that in mind. Just as an easy example, Ademan is 19 for another 60 or so days. He's only hitting .218/.306/.300 so for those not really paying attention you might think he's kind of a bust this year. But he's 19 at Myrtle Beach where the average age ofr a hitter is 22.4. You're talking roughly 3 years older than him.
Typically speaking, if you're a college player it's rather unlikely for you to be well under age for a level until like AA/AAA. So, in the case of Lacy, him being 22 and starting in A ball this year I'd argue he's maybe a little behind where a top tier college prospect might be but it's not like he's 24. And the way I factor that in is you take your normal expectation for a guy at an appropriate age and expect slightly more. Again as an example, if you want 8 k/9 and 3 bb/9 for an average MLB player then vs similarly aged competition you also want that in the minors. But for someone who's a little older you may want to see say 9 k/9 and a better walk rate.
Getting back to k:bb ratios, 3 is pretty decent. Think that's where I'd put the starting point for being a "prospect." If you're below that you're probably just organizational filler. For example Jen-Ho Tseng is kind of a fringe #5 type pitcher. He had 442 k's and 149 walks or 2.97 K:BB ratio in the minors. Once you start getting over 4 you're likely a mid rotation type talent or better. Hendricks as an example was 4.77 in the minors. The elite of elite guys might get to 5 but honestly it's kind of rare that it happens because typically if you're performing that well you're way better than the level you're at and you need to be promoted.
Now obviously context is important here. You look at someone like Chris Archer in the minors and he's below 2 k:bb rate. However, in his case it wasn't that he couldn't strike people out. He just lacked command. He was regularly posting 4, 5 and 6 bb/9's at various levels. And there's certainly examples of guys who are way too young to be at a level who don't perform that well.
To summarize a bit here, typically what I look for in someone to be excited about is a 4+ k:bb ratio and someone who throws ground balls. The second part isn't as important but it's kind of the philosophy the cubs run with. They want pitchers who throw ground balls to athletic defenders behind the pitcher. So, often times the cubs starters wont be that interesting from a k:bb ratio standpoint. In AAA they have a lot of guys who don't get K's but throw tons of ground balls. And that's in general why their pitching is viewed poorly by prospect people.
