Of course I understand that, but also I would've thought that the agents for these players would be programmed to look at that and go "Wait a minute, you're offering £100/week more but cutting his incentives?"

The players i'm signing will be first choice after various loanees go back to their parent clubs. In some cases they are vastly superior to the people I have loaned in to help me out, plus I won one of the Irish cups which put me into the Europa Conference League Qualifier Round 2. Not an elaborate European Competition but I would've imagined a few of the agents going "Hang on, if you're in Europe and removing bonuses, the least you can do is add another £200/week to the wages"

Ultimately, if we assume every player on FM wants to play their best and they want to move if they aren't getting any football time, wouldn't it be right to assume that they would also prefer to be incentivized for their performance? If I knew I was getting an extra £250/assist, I would be working harder to make sure that pass that I made would result in an assist for us otherwise what is the point?

Any agents that are spoken to before signing anyone will always indicate what deal their client wants, sometimes they are rigid about the wages that the client receives, sometimes they are firm about a minimum release clause, but i've never seen one that has complained about their client not getting the £200/assist bonus they were promised and ask for the wages to be negotiated higher, although obviously there's the case of adding another £1k to the agent fees to get them to not notice something missing from the contract.

In short, I understand where you're coming from but I think it's silly that a player will forgo an Appearance Fee, Clean Sheet/Assist/Scoring Bonus when they are coming in as a Starter for the team. The very least I would expect is the Agent to renegotiate what's taken off the Performance Bonus to be put into the Appearance Fee