A few points...
I have never gotten wrapped up in the "MS saga", or at least that is not my reason for wanting us to sign a DM. That would be stupid. For the majority of last season I consistently said both on here and to fans of other clubs that despite what the 'Goals Against' column might suggest, our defence is not actually that bad. We now have a very good defence with the additions of Alderweireld and Wimmer that boasts quality, variety and strength in depth.
Yet I still want to see a DM come in. Regardless of how much Mason and Bentaleb could improve this season, it would be folly to assume that just because they have potential, we shouldn't be looking to compliment their skill-sets with someone more defensively-minded (or experienced, as someone mentioned above). Even if they become more defensively minded, with the departure of Capoue and probably Stambouli, we need another such option in our squad anyway. It is the only prudent course of action if we are serious about CL qualification.
Also - we are not Arsenal, and even if we did have such a technically adept team as they have had over the past decade (we don't), with at least 2 world class players at basically all times (we have zero), to say that we should not sign a DM for such reasons alone is myopic, and is exactly what we have all criticised Wenger for in every single season since Vieira left. Why is such a policy suddenly logical just because we're talking about Spurs?
Obviously we need another striker (and an attacking midfielder(s)). But just because one signing is necessary, or even a priority, doesn't mean the others should be neglected. You don't hear me calling for us to abandon signing attacking midfielders and strikers in order to sort out a DM... They are all important signings, and if we don't cover all of them by the time the window shuts, I would call this summer a failure.
Thankfully the links in the media suggest we are looking to sign all three players, or at least two players to cover those three positions. It is going to be a massive ask to come above City, United or Arsenal this year regardless of who we sign, but if we resign ourselves to mediocrity and think 'oh, that'll do' then we have absolutely no chance.
/rant