Ighalo for Greenwood is like for like.
Mata for McT - taking off McT makes sense given his recent return from injury. I'd rather Mata than Lingard or Perreira, especially after the promising display between him and Bruno against Bruges.
72 mins in, fresh legs, trying to galvanise the team for a winner. Both of those looked fine to me.
Willams for Martial on 89. Presumably Ole felt that Everton were the most likely team to nick it, which I'd agree with, and he wanted to shore up for a point.