You're massively overestimating Martinez. I doubt he's doing any real coaching at all, but if he is then it isn't visible on the field at all.
I think he's only playing one game (against a weak team) to hide how terrible his tactics are so he doesn't get fired.
I'll give a recap to show how terrible his coaching is:
* Belgium draws a crazy easy group for de qualifiers. Martinez quickly starts using a 3-5-2, which worked well again our opponents. The reason it works is because we're attacking with 7 player and therefore creating more chances. Personally i was still very much on the fence at this point. One of my biggest gripes was that Martinez built te team around Hazard and had no idea what to do with De Bruyne and moved him around a lot. It's seems like the most obvious thing in the world to me that would use a De Bruyne to be a playmaker, but not to Martinez apparantly (using KDB mostly as a winger or DM).
* After qualifying we have 2 practice games against Mexico & Japan. Our first decent opponents, although not nearly at the level of elite teams (like Brazil, Germany, etc). So the first game was against mexico and the 3-5-2 got exposed immediately. Having 7 attacker is fun, but when you're playing against a team that can counter then you're suddenly giving away a massive amount of chances. Despite Hazard having a brilliant game, we still tied 4-4 because we gave away a stupid amount of chances. In his postmatch interview, KDB was pissed and (correctly) said the tactics we used were wrong. Cue a massive amount of press (De Bruyne vs Martinez!). But it's clear KDB was in the right (he seemed to be alone on the midfield for most of the game) and it was just insane that Martinez watched that game unfold for 90 minutes without interfering.
* So after that shambles we play Japan. Would Martinez revert to our classic (and defensively much stronger) 4-4-2? Would he still use the 3-5-2 but maybe instruct the winger to pay attention to possible counters? Or would he do the exact same thing as last game? The last option ofcourse! In another atrocious game where we looked the inferior team in the first half, Martinez FINALLY reverts to a 4-4-2 in the second half ... only to quickly take KDB off the pitch. So now we have a fairly solid defense, but little offensive creativity. With some luck, we managed to win 1-0 in a horrible display of football.
* And now we're playing against the mighty Saudi-Arabia. And what did Martinez say in an interview today? That he isn't going to experiment with the tactics at all. So he can use his attacking tactics against a weak team again and brag when we win. But hey, he says he might give Nainggolan a chance to prove himself. So one of the best midfielders in Europe (who's in the CL QF) has to prove himself, but you can be sure that this twat is bringing Chadli (not even in West Brom's squad anymore), Carrasco (moved to china and is doing horribly), Witsel (been on the decline in china for years), etc.
Sad truth is that he doesn't like Radja because he doesn't approve that he's a smoker. That he's also one of the hardest workers on the pitch doesn't seem to matter.
Honestly, i don't even see us getting past the group stage on the world cup.
/rant over.
️ Mignolet, Meunier, Alderweireld, Kompany, Vertonghen, Witsel, De Bruyne, E. Hazard (c), Mertens, Carrasco, R. Lukaku