If someone would ask me at the start of the season if Koeman would deserve another season if we win Copa, go out somewhat respectable in the CL - at least for our recent "standards", lol (I know that home loss against PSG was bad but with a better finishing - also Messi scoring that pen - we could potentially get back into the tie in 2nd leg) and be in a title race in May I'd say he absolutely deserves another go. These were my expectations before the season with a rejuvenated team (which in most games was even younger than expected due to injuries) coupled with unhappy Messi, a lot of misfits and other veterans who were underperforming for years and are physically and/or mentally done so I had no expectations for them to suddenly turn into what they once were again.
Then after a bad start (which all things considered was expected as well) if someone would say to me in December we will be in a position to depend on ourselves to win La Liga after being 10 points (with AM also having a game in hand IIRC) behind my answer would again be Koeman's done a good job to bring his team back and deserves another season. Sure, when you're that far behind you need the leading team to start dropping points (which happened) but you also need to continue to win to put more pressure on them (which we also did) for 3-4 months.
If start of 2021 was one turning point (to a positive) then I think CDR final was the other one (on the worse). Normally we would expect winning a trophy in a dominant fashion would be a morale boost for the team for remainder of the season. But it was the other way. Sure, we've still won next two games but we were not really convincing against Getafe (even with a 5-2 win) nor playing against 10-men Villarreal side for 30 minutes. What happened later against Granada, Levante and Celta could already be predicted from those two games.
I think this is mainly up to three factors:
1. we were closing the gap to Atletico so pressure on the team raised. Catalan media started to talk about our chances to win the league and even the most pessimistic fans were also starting to believe we could do it and calculate how many points AM still needs to drop if we continue winning our games etc. And as we've seen many times with veterans inside our locker room over the years, whenever they're put into any high pressure situation it usually didn't end well so it's hard to blame Koeman for that. Other coaches before him have failed too in that aspect and I think until mental midget like Alba and physically done players like Busi and Pique are still here we'll probably go through another two coaching changes and nothing concretely will change until they'll finally get a big thank you and goodbye letter from the club. So from that standpoint I don't believe it matters much if Koeman stays or not.
And if those players who are supposed to lead the team are failing to do that then it's hard to expect younger players to bail us out. We have some good talents (who some people were too harsh on imo) who could turn into good players for this club in future but they're just potentials at this point. None of them is a 19 years old Messi. And I think even he would struggle to develop into what he's today if he'd be led in his teenage years by our current bunch of veterans instead of having people like Puyol, Xavi, Henry, Eto'o, even Ronaldinho (despite him not living exactly a sporting life in his later years here he still had a positive overall impact on Messi's career) around him. Pedri, Dest, Oscar, Araujo, Ilaix, Trincao... were never the players who were supposed to bring our success this season so it's harsh to be too critical with whatever they've done.
2. This was the second biggest mistake (I'll come to my biggest complain about him in point 3) of Koeman but is what I believe the main reason to our downfall in last weeks and will probably lead to him losing his job. It coincides with the return of Pique and Roberto to the team and straight into the XI when they were clearly both not ready to take on whatever expectations Koeman had for them even if they're one of our captains. But captains only on paper, we don't really have true leaders (which is linked to point 1) so they didn't bring any leadership to the team and at the same time were also physical liabilities. Pique is just done at his age coming off a serious injury. Roberto was affected by corona and injuries this season and I think his physical level will improve next season but would still prefer to move on from him. If we won't find a buyer (very likely) then keep him until his contract expires next year and use him exclusively as a 5th/6th choice midfielder and then let him go.
3. I have pointed this out already a few times and I've also said before/at the start of the season that Koeman will probably have a core of 15-16 players he'll count on most of the time and others will have to convince him strongly to get playing time. It's exactly what happened. Sure, I was wrong about some names (with Pedri who was initially on Koeman's "go on loan" list turning into a starter being a prime example) and injuries have also shortened his list of "reliable" players with Pique, Roberto, Coutinho and Ansu missing most of the season so in the end we were just down to "once de gala" and Ilaix being our 12th man in the most important game of the season.
Sure, our bench is not the greatest but a sign of a good manager is getting the most out of what he has at his disposal. I'm aware that every coach in the world sees things differently, they all have their "favorite" players (which fans usually disagree with) and those who they don't see as a fit for their system for some reason(s). But at the same time you also need to be smart enough to know it's almost impossible to get through the "normal" season utilising just "your" players. And even more so in this corona era with basically no rest for the players between last and current season and even more congested fixtures than usual.
As said above we've had some longterm injuries (to what would surely be important players for Koeman) but we were never in as bad situation as RM for example where in last months often happened Zidane only had 2-3 first team members on the bench due to injuries or corona (which our players mostly and thankfully seems to have avoided). OTOH Koeman had healthy and fit to play Puig and Pjanić on the bench but choosed to ignore them for reasons only known to him and instead run our starting midfielders into the ground. I'm not saying he should've started Puig or Pjanić in big games if he doesn't trust them enough but they're good enough to start against lower table teams occasionally to "keep them warm" and be ready if/when they're needed. And with more playing time you have better chances one or both of them will turn out useful squad/rotation players and gives you more options (and as a coach you should always have alternatives because you never know when you'll lose a player due to injuries or suspensions).
Similar could be said about someone like Firpo. Again, not good enough to be a starter but nobody could convince me he couldn't do at least respectable job against Alaves, Getafe etc. to give some rest to Alba. Or I'd also prefer him as a LCB ahead of Umtiti and even Lenglet with his struggles this season. Firpo has done a good job against Mbappe in 2nd PSG game and I think he hasn't played since then.
Trincao has also done well when he has started a few games but Koeman continually used him as a sub where he wasn't as good. Mostly because he was usually thrown into the game for the last 10-15 minutes when we needed a goal and were playing with 5 forwards, lol. Or after the change of system he was used as a RWB which is clearly also not a role that fits him. Why not start him every 3rd/4th game to build his confidence and maybe turn him into another useful squad player (which is what should be expected from him at this stage of his career).
I'm not saying any of these players is a difference maker on individual level. But they should've all been used better, get more consistent playing time which would benefit both them and also starters who would get more rest and be kept fresher for the end of the season. As said above I think our struggles in CL and big games in general are mostly in players's heads but at the same time it's also clear most of the starters are also physically exhausted because they were overplayed. These are totally self-inflicted wounds which could be prevented if Koeman would use his squad depth better (which is obviously far from ideal but also better than what he thinks imo). But he's either too stubborn and/or tactical inept to do that.
And that's why I'm leaning towards him leaving despite our results being somewhere close to what I've expected before the season (and better than expected in mid-season) and some overall good things I like with him, especially giving a lot of minutes to youngsters which could benefit us longterm. I'm also usually for establishing at least some consistency and changing coaches every season doesn't help in that regard nor I'm convinced that whoever might potentially replace Koeman will actually be an improvement. It's also very unlikely that a new coach could do much better until underperforming captains will still be unquestionable starters which I'm affraid they'll be as long as they're here. Really hope to be wrong though and that we'll manage to phase them out of the lineup and eventually the club sooner rather than later so we can finally move into a new direction. Only time will tell if that direction will be good or not but I'm prepared to see what future we have now rather than keep status quo for 2-3 more seasons.