I have had a horrible first season with Ronaldo, which ended up with me finishing the PRM as 5th (luckily I won the CL, otherwise I would have been fired).
At the beginning of season 2 I have now made some minor tweaks to my team tactics, using a bit more width at home and away playing down both flanks. I have Ronaldo on slightly above middle closing down, of course runs on often, the rest depending on the stats simply.
Suddenly he does not only play much better, he also scores more.
So maybe you just need to tweak your team settings and your crossing settings (cannot remember here at work atm how exactly I tweaked the crossing, but it is at least on mid and the crossing from set on mixed) a little and he will start playing properly.
Actually what helped me a bit was reading through Dayle's tactics guide for dummies

Not that I read anything new, but it simply made me reconsider my tactics and check if everything is reasonable in there, since I just used my old "success" tactics without much tweaking.