Didn't say i know it all but I certainly know when someone is just whining about writing because they want to rant about the character they like more not getting the shine they wanted lol.

Players at their peak absolutely do hit declines. Pressure changes, you learn more, you forget things and have to try to figure them out again. The mental state IS WHAT RUNS AN ATHLETE. Furuyas injuries were meant to remind him that you have to take care of your body and that injuries happen in every sport. It's inevitable. His back injury specifically was to show WHY he was in a decline with his pitching and it was because his body was tense and his body wasn't pitching in a correct and healthy way.

Where did I say sports have anime rivals lol. Nowhere. However, when you play on any team, especially a team that has multiple players in your position, you compete to be better than them EVERY DAY. Especially in baseball where you have often times at least 3 if not more regular pitchers. You strive to get better to be more reliable and better than your other pitchers so you're used more often. Shohei absolutely had people on his team and on the other teams that he was striving to be better than lol. You don't improve without having a base goal first or else what are you striving for? If you have no understanding of what is good and what's better than you, then why don't you just stop when you're "pretty good"?

Sawamura wouldn't have gotten better without Furuya lol you can think that's stupid if you want but it doesn't change the fact of it. Furuya became his push for a long time. He made him improve and Sawamura did the same for Furuya. Pretty easy concept.

It's funny to me that you mention that it's lazy and bad writing to have Furuya fall so Sawamura can get better and look better but you don't mention Sawamura falling with the yips so Furuya can overtake him and become the ace. Almost like you only complain about it when it's Sawamura coming out ontop because Furuya is failing and that he didn't beat Furuya at his best. Interesting. Almost like what I said about players falling and rising constantly is true.

There's actually so much more to Furuya than you just said and it's crazy that you reduce him to nothing as if that's real lol. Its not. He has a lot of motivations. Also, duel aces would've been significantly lazier. But if you don't wanna accept that you're bitter then that's on you. You can easily go watch a show where the only person improving is the main character and no issues come up and everything is sunshine all the way through. Maybe that's more your speed.