I hate the idea of determining a player's ability by how much he gets paid. You could literally just buy a good player then (even if he was crap when you signed him!) and loyal players who signed on for less to help their teams would be disadvantaged, possibly to the point of getting dropped.
Just don't have financial contracts. There's a very good reason we don't have them in CricSim and it applies to this too - there's no incentive for players to sign for more money unless it'll make them better players, in which case there's no incentive for clubs to sign good players as they can just make anyone they like good. You need to find a way to make players want to sign for more money without actually making them better players if they do so. If you can do that you're a better man than me. Else you need to scrap it.
It is not like paying them a huge wage will make them orsm over night. Post rank and Past performances will be the major factors in how good a player is. I doubt I can, but I will give it a go
It could have to do with a specific attribute like fitness which does not have a massive impact on the skill of the player. Just means they play more games in first. It makes them better as a player to some degree but not to a great extent.
Similar to the idea I had for CricSim whereby your salary improved your secondary skill, whatever that may be. Didn't end up going with it though as aside from being unrealistic, I had no idea what to do with allrounders. I can see it working okay with this though; good idea.
The only way for it to work properly however is to make sure that your player improves regardless of playing in firsts or seconds.