He was training with the first team and while he rarely got a chance under Xavi at the same time he played regularly for BA. He started 31 games including promotion playoffs and also played full 90 minutes in most of them. I think he has improved a lot under Rafa last season. Clearly wouldn't play on current level if he would need to start games for the first team 10-12 months ago.
Don't think he's a world beater and probably won't stay long term (you never know though) but for the time being he's a very useful cheap squad player who I think can do a solid job against most La Liga teams. Will probably be exposed vs better opponents and will need help of his team mates but that's true for any player used in his role.
He's also another good example (besides Fermin) that you can also still get a chance in the first team when a bit "older". Kids shouldn't think they'll never make it here if they don't play first team minutes at 16/17. Just stay patient, work hard and doors of the first team will always be open for you.
Will be hard over the next few years as most talented youngsters will expect they are the next Ansu, Gavi, Balde, Yamal or Cubarsi and they deserve a chance in first team at a very young age but if we want to return to be a normal club (and when finances will improve) then we should allow kids more time to develop.
Will probably prevent some of them getting long term injuries before they turn 20 and both the players and the club will benefit from that long term. Some of them will surely also run out of patience (that happened before so won't be something new) and leave so it's good we also have likes of Casado and Fermin on the other side of the spectrum to put things into another perspective how player's development (or integration to the first team) should work under more normal circumstances.
As good as La Masia is we won't be a serious club again before we won't need to force teenagers carrying as much heavy weights as they had over the last 5-6 years. Yes, it's always exciting when new youngsters emerge but it's not sustainable depending on them so much long term. At least not for the club that is expected to compete for all big trophies every season.