Makes sense to me like, he is clearly not going to make in the Prem. Make some decent cash, play in his home country a far, far nicer country to live in when you're earning a massive pay package. Why not, go for it bro.
Be sad to see him go as he has done well for us. He was a £5m buy in the championship - not an 80m epl standard defender, limited and bailed out by his pace a lot of the time but gave it his best and generally didn't make to many howlers. Hopefully that means Kraft and Manquillo are the RB's for next year, Dummy + another for LB, CB is fine so we can focus on finding another CDM, winger and striker. Give me 4 decent, EPL experienced, players - Brooks and Wilson/King from Bournemouth would do for the latter 2 positions, the aforementioned LB (Willems) and one to come in to support Hayden, Shelvey and Slongstaff in the CM and I'd be reasonably pleased with our squad, but with hopefully a few more out the door over summer who'll need replacing - Atsu, Murphy, Aarons, Saviet - he is contracted until the end of next season ffs...