I'm pleased he had such a good game the other day, and hope he keeps it up, as I did the last time he had a good game after being dropped.
I think he's been largely average and sometimes worse this season with little in the way of mitigating factors. Lukaku often has poor games with back to goal but then scores a brace in it, which at the end of the day is his job above all else, so you have to say he has done well. If Barkley was largely anonymous and then did similar with goals and assists, I'd be made up with him. However, he has 2 goals and 2 assists in 15 despite being a set-piece taker and a number 10.
He's now 23 and the derby will be his 150th appearance for club and country (excluding loan spells). He's actually a pretty experienced player now. If he doesn't score he'll have just 20 goals to those appearances and probably a similarly low number of assists. It's clear a player that talented could be doing a lot better, which i think is where the frustration comes from.