If we bought Maddison for £100m, and sold MGW for £100, five year contracts, we'd be up £75m on MGW with a £20m cost for Madison for the year. Gives us £55m free!
That's a good reason, there are others. He's younger and may be better one day. He already has an understanding with Johnson and Johnson is becoming more important for them it seems. They want more than one player in every position and are rich. They want someone with more legs than Maddison who tracks back more. Etc etc.
I like Domínguez - I think there is a player in there (but the same is true of Freuler, and he didn't really cut it in this league) - but if we could get reasonable money for him I'd probably sell. There is always the risk that he could be a Mangala (& let's hope Sangaré) who took until his second season to really blossom, but Nuno doesn't seem to rate him much, so could be a goer.