I found these two books a mixed bag. I like sports m/m romances, in part because I like learning more about these worlds through the lens of specific characters. However, the fact that KC is an aspiring baseball pro is not really central to the story. It's important in KC's life, but it could have been any other sport or, for that matter, particular skill he was recognized for. The story isn't set in that world, it's just a sideline. Also Charlie, while apparently very interested in music, doesn't ultimately follow a musical career.
If the two books (which are part of a series) are considered one story, then this does have a hopeful if not clearly HEA ending, and it does focus primarily on one relationship. So it does fall into a romance category. But I found them quite unromantic for several reasons. One was because of the get-togethers and breakups (and various other hookups etc.), as well as the overall uncertainty and unclear definitions of the relationship. Another was that the sex was barely discussed, despite being key to the attraction between them, and in at least one case there was an incident of anal with no lube or prep at all as if this was a perfectly common thing to happen.
And then there's the problem with the protagonist, Charlie. The longer the story went on, the more I disliked him. He's insecure, dishonest, thoughtless, and indifferent to most people. I started to wonder what KC could possibly see in him, especially after the first part of their relationship where his admiration and uncertainty could have been seen as flattering. The fact that Charlie then improbably has a couple of crying jags scattered in the story struck me as both out of character and left me more annoyed than anything else, given that he didn't seem to care about anyone else's feelings.
One point to mention is that these two books are from Charlie's POV whereas a middle book in the trilogy is from KC's, although apparently it doesn't have much more about baseball since it covers a period in his life referred to in the third book. My only interest in it would be to learn more about KC's backstory, primarily his younger years, but I would assume it provides KC's own reasoning as to his attraction to Charlie.
I didn't appreciate the casual racism in the book, and a jab at the idea of cultural appropriation. It occurred as asides in a few places, but that always leaves me less forgiving a reader.
However, the books were a quick read -- I zipped through both of them, and I definitely didn't anticipate where anything was going, which is a big plus. As an overall arc of two people's youth to middle age, I thought it followed a believable path. Also, though I've never considered myself a sentimental sort, I could have used more of it here. But the absence of a lot of emotionally dramatic scenes certainly made it easier to keep rolling through the plot. I also think that the longer the story goes on, the more sympathetic a character KC becomes.
I guess ultimately, if I used the Netflix model, I'd rate it three stars. I wasn't sorry I spent time reading these, but I have no interest in re-reading them and can't offer an enthusiastic recommendation.