That's a bit unfair, O'Brien has played out wide and in midfield as much as he has played as a striker and he has thirty one goals in one hundred and sixty four appearances overall for Millwall according to Wikipedia - he's also played and scored for the Republic of Ireland.
As for Thompson, he's been a regular starter this season and I think you are seriously under estimating his ability given his Wikipedia entry
https://en.m.wikipedia.org/wiki/Ben_...er,_born_1995)
I watched five City players not look out of place at all yesterday in a good Wales Under 19 team in their match with Russia. Sam Bowen and Keenan Patten both started the game and played a big part in wresting control of the midfield from the Russians with their contrasting styles - they both looked good players at this level.
Harry Pinchard was an energetic and effective half time sub whose arrival coincided with the Welsh midfield's best spell of the game, while forwards Isaac Davies and Dan Griffiths made a good impression as subs with the latter winning a penalty in the last ten minutes - for a while, there were five City players out on the pitch for Wales.
Goalkeeper George Ratcliffe and attacking midfielder Sion Spence are both doing well on loan for a Barry team near the top of the Welsh Premier League with the former in the latest Wales Under 21 squad with Cameron Coxe. We have a strong group of 18-20 year olds currently and there are others I haven't mentioned who have a chance of making a good career for themselves in the game. If such a group were coming through at other Championship clubs, I'm pretty sure they would be getting first team chances and I'd say that, based on what he did at Millwall, their chances of getting game time for the seniors are better now than they were under Neil Warnock.