The midfielders being named are all very good players and based on overall performances and the expectations of the prem, they probably deserve a start ahead of Gaston. I personally believe Gaston offers something nobody else does.
I always recall WBA at home last season. We could have played them all day and not scored. Gaston came on, played a chipped ball over the top to Lallana, and we win 1-0. I don't believe any of our midfielders, with the exception of an in form Tadic can produce that moment.
Wages are obviously a factor with Gaston. But for pure footballing reasons, we lack a real option to change a game. Sometimes he won't, but he has the ability to. Creative ability that is lacking on our bench, and our first 11 given the number of chances created yesterday.