Some big calls there mate - only one I'd disagree with is Fellaini - Barkley. Different type of players. Arguably he's replaced Fellaini with Barry (for DM) and Kone (for winning headers up front and holding it up). So very mixed results.
Key one is Pienaar - Cleverley though.
It's obviously difficult to judge a players quality under Martinez as most of them tend to see their form nosedive so some of them might go on to be decent players.
Let's look at a typical Moyes midfield with everyone fit.
Pienaar Cahill Osman Carsley Arteta (you can move the players around, swap Gibson for Carsley, Fellaini for Cahill etc.)
That midfield has balance. Physical players and nimble small players, aerial ability and footballing ability on the deck, set piece ability, goal scoring ability with the ability to cover the defence. Most of those players could captain or did captain the side. The only thing missing is pace really.
Look at Roberto's line up at the beginning of this season
Kone Barkley Cleverley Barry McCarthy (Lennon or Del can swap for Kone)
There is pretty much zero aggression in that midfield (the odd but by McCarthy aside), in terms of flair you have Barkley and that's it. The midfield has zero aerial ability and Barkley aside can barely muster a goal between it. None of them can hit a set piece, the interplay between them is barely existent, they offer zero cover for defence and apart from when Lennon is on also has no pace.
What was a very good footballing team with a dross striker at the top has been replaced by an absolutely woeful midfield with a 30 mill striker at the top.
Martinez has brought in some decent individual talents but he's utterly stripped the team of genuine footballers with the only ones remaining now being Stones and Baines in defence.
The days of Pienaar Osman Arteta Baines making Gary Neville's head spin are long long gone. Our midfield offers nothing to hurt anyone now.