Similarly level 7 manager here.

Has your midfield got less players than the opponents (so the player had to cover more grounds than he could, hence the yellow cards)?
Or did your formation require your MC to help defending in areas where he cannot do efficiently (eg. MC down-arrow marking an AMC)?
Or is it just that the opponents midfielders are just way better (1*+)?

If neither of the above, then try observe some 10 more games to see if this card pattern still persists. If so, you may consistently need to keep a very good sub with MC+1/2 positions in the following seasons to avoid this MC getting 2nd yellows. The likelihood is you would want to keep using him as lots of resources was invested, so just see how it goes.