Whats his stats like so far? Is it just the rating lacking or is it passing/heading/shots? Also whats your tactic and his role in it?
I had a similar situation when I first bought him for Boro, not sure how much was tactic and how much was him just being new. First time I told him "I Expect A Performance" in a pre-match teamtalk he played great, I think its because of his Attitude and Determination that makes him rise to the challenge where younger less determined players would crumble under the added pressure.
I use 4-4-2 Diamond which has worked well getting the FC (Cardozo) to interact with my AMC more than the flat 4 midfield tactics. List him as a Target Man, tick the box, then set to play To Feet, will still get pleanty of headers during the game from clearences so unless opponents defenders really suck in the air I don't bother setting that, and I certainly don't want to have him trying to Run Onto Ball.
For possession tactics I set Cardozo to Rarely play Through Balls so usually passes it back (to the AMC) who can then use his creativity+passing+dribbling ect to exploit space created by the opponent closing down Cardozo. I up Through Balls to mixed for when there is more space (such as behind the opponent playing a high line) so more likely to put the other striker through on quick attacks rather than passing it back.