What are the reasons you would want to change a winning team?
We need to set up defensively like we did against Liverpool. Surrender 65% of the ball, but keep the shape. We'll have Cleverley, Delph, and Westwood protecting the centre halves and Gabby harrying everything around the centre circle. I think everyone agrees on that.
We'll get the odd counter, and the odd long ball for Gabby to chase, and maybe even a decent cross or two from Andi. But I suspect we'll be short on chances, and I think just about everyone would expect that.
By bringing Jack in for Kieran Richardson, you add a little bit more attacking threat. Kieran's been very good and it would be harsh to drop him, but he doesn't create as much as Jack does. And I reckon we'll be more short on creativity/chances than anything else. With Cleverly, Delph, and Westwood also helping out defensively, Jack wouldn't be left as exposed as he would be in a 4-4-2.
Also, it's Arsenal. I wouldn't fear for Grealish out there. Either in terms of getting kicked about or being too intimidated by their prawn sandwich fans.
What you lose is a solid performance from Richardson, and gain a little bit of a spark. Think we might need creativity more than another solid midfielder.