Gomez stepped up after Ibrahima Konate was forced off at the break.
Slot said: "Yeah, that says a lot about his mentality. That also says a lot about his quality, if you don’t play that much and you come in, in a game where your teammates were outplayed for 45 minutes, that you can come in and play like this.
"And it also says a lot about his mentality in recent weeks and months, where he didn’t play that much, but he is now able without playing a lot to play 90 minutes on Wednesday and to bring in a performance like this on Saturday.
"But this is what people told me when I came in: Joe is a top, top, top professional who always, no matter what position he is in, gives his best for the team and for himself in the end as well. He got the reward for it today because I think the fans loved what they saw – I definitely did."