The last anime series was...what, four years ago? Yet they really painted themselves into a corner at the time. As far as I can tell, they juuuuuust caught up to the manga, using up all their material - and then shortly after, the manga writer took a year's leave. I get the impression that it's been a slow restart for her as well -
The way the story's going, it would suck to have a 13-episode anime season next - we're going into a long, long training arc here, with lots of personal stories and diversions like the trip to Koshien thrown in as well. And since the beginning, Higuchi-san has shown that she's setting up a long, complicated,carefully-thought-out plot in which we're expected to know the names and characters of a lot of players on a lot of teams. Things like the friendship between Kanou & Mihashi, the fate of the catcher who's blackmailed into injuring players, the former captain of Tosei who's actiong as a conscience for the ethics of the game, the mystery of Momoe-san's high school managing experience...there are so many slow-burning fuses built into the story that I hope to be seeing them resolved over the next 10 years or so.
What matters is the manga's popularity in Japan - as long as it's selling well, we have a good hope of seeing another anime season.
I think you're very right in your assessment of the current state of the story. Even though almost everything centers around the sport itself, the author really has built an extremely complex story with a wide variety of separate components all being explored at different times throughout. A really outstanding job of story telling so far.
And yeah, these things seem to happen all the time with anime adaptations of ongoing works.........I suppose it's understandable for the powers that be to try to capitalize on a work's current popularity, but it can lead to some disappointment since they often create artificial endings for the anime versions. Not that I'm saying that's how this one is, I haven't watched this one...........but that's often been my experience in this situation. In the past I've watched many animes and then gone on to be shocked that the mangas were still running..........kinda made me wish I'd never watched the anime version in the first place. But I usually prefer the original written works anyways