Did they?
Jagielka, yes.
Mirallas was here for a season, he was out with an injury for half of it, while Moyes was here. Looked at his best in RM's first season.
Barkley played three times under Moyes. Three.
I'm not blaming Martinez for Koeman's mistakes. I'm not even actually having a go at Bobby.
I'm stating the simple fact that Martinez signed players for his system. He wasn't thinking he'd get sacked, he was sure it would work, but it didn't and that style (or attempted style) took us backwards. Our squad is incredibly inbalanced, with loads of 'safe' central midfielders who were good at retaining and recycling possession. Now they're pretty much useless as most teams figured us out so quickly in the last two seasons.
So, give Koeman the chance to bring players in that suit his style (like he did at S'ton) before jumping on his back about everything or saying I'm moving the goalposts - I ain't.