I asked him a question that was a bit similar and I do have the feeling that he doesn't have a great musical freedom with BCC (and especially with BCCIV as all the songs were composed by Joe and Glenn).
To reassure you, I have listened to the whole album and there are some serious moments where Derek shines with a grand piano, an instrument that he only used in The Great Divide (in the background and I'm pretty sure it was not a real grand piano). I can't post a full review until the week of the release but I have to say that I was really pleased and surpised by that album.