I understand he's old, but S. Cazorla has possibly been the best Spanish midfielder statistically in La Liga since his return from injury. He's started the past few games for Spain as well.
Matip, a player who started a CL final wasn't picked up as well. Kloppo said he's world class.
Dusan Tadic plays a different position, but he leads Ajax in goals and assists. It's not like he was a terrible player in the PL either, he was pretty good.
Lucas Torreira, Leando Parades and Lucas Pacqueta have had terrible seasons, but I think all 3 of them still have sky high potential.
Bonucci sucked for Milan, but seems he's having a bounce-back year for Juve. Surprised he didn't get picked up since he's probably one of the best ball playing CBs around.
Glad no one brought into the Wilfred Zaha hype, probably the most overrated player in the PL.
Donyell Malen, Odsonne Édouard, Filip Kostic other names I was considering at times.