On loan it would seem like really astute business. Someone reminded me earlier that having five subs makes it much more palatable to sub out a center back if needed to switch the system. I was thinking of the times we've had to switch formations from 3 at the back to 4 at the back in second half.
Still does feel like kind of an awkward fit to me, though. While I'd prefer it was Keane or Holgate that was sold, you have to assume it would be Mina sold to make way. If that's the case you could end up with a Coady-Keane pairing at times depending on injuries or form, which honestly sounds like a nightmare. But at full strength him and Tarkowski would give us leadership and passing ability, two things that we've sorely lacked from the position in recent years.