soccer manager... c'mon, get it right
and you gotta let your wrist flop around limply as you say it, too... it's a formality so that the write message is communicated.
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prelude: lol written after "first,..." so, i just want to mention you can turn this feature off. same with personalities. basically everyone will have "100's" for each of these traits and morale would be "normal" so, you lose the negative effects, but also any positive ones as well. it's all neutral.
first, put things in proper perspective... those angry red faces aren't nearly as bad as they look. you are not being admonished, and no one is voting you worst gm ever.
morale is not likely haveing as severe an effect as you are attributing to it. so, if they are lingering in unhappy times... it's not too big of a deal for a better team... and if you are a worse team it doesn't really matter if you win 70 or 75 games, because you still miss the playoffs.
(totally guessing on a 5 game swing, but i doubt it's that large - 5/162 is pretty large percentage for a small thing.. even in a terrible environment, players still play for their next contract, so i hope the ddidn't rationalize too large of an effect)
a middling team it can be a concern... if you are on the edge of making hte playoffs, it may be worth your effort to do something - but smaller is better than bigger still, because morale isn't a switch that turns on and off. imo limping into the playoffs to play decidedly better teams is worse than losing a few more games and getting a better draft pick next year... worry about morale after the season in that situation.
the "current" state of morale a calculated value that changes dynamically over time due to numerous factors that you can easily guess through the ui and what metrics are availiable and displayed to you. so, it takes time for it to +1 or +2 it's way back upto "normal" (=0) or "happy" (greater than some value higher than 0 but less than 5000 because ecstatic is another tier above happy)
if the net effect on the team is negative, it will never recover in that instance, but you shouldn't assume that after just a few months of a previous change. if moral is "-5000" (scale isn't important, made up number) and your 'improvement(s)' are only adding up slowly per calculation (daily? weekly? not sure when it does these computations, but it's continuous and predictable as to when), then it could take a very long time to "fix" it.
only way to know if your cahnge has an effect is to simulate ahead then restore... bit like cheating though... i'm willing to do something like that if it's only during the learning process... i've never bothered with this specifically, but i have learned a thing or two about how the game works by doing similar things.
e.g. i'd suggest everyone plays at least one 100% accurate scouting league at least a few years - fictional or real, but if real yo uneed to know how things change after real players are replaced, too. so that takes more seasons to learn. you start to see how things muddle things up - even turn off the side stuff like personality, coaches, etc... only on-field modeled stuff. you start to understand how innacuracy is applied, how much morale and personality actually effects development etc ... if you see roughly the same results.. guess how much those tihngs are really changing things - i'm not saying ignore them, just put in proper perspective relative to the importance of actual talent (the real skill ratings, like contact, power etc).
bottom line: do not give away good talent unless you have a suitable / equivalent replacment... it is likely better for you to deal with a bit of a morale problem than reducing talent by any noticeable amount even in only one everyday player.
accumulating enough good players for a 3-5+ year window of success is the most difficult and most important task. casting off good talent is very rarely the right thing to do.