I think the obvious spot for Diaz is Blum's, or maybe Seger's. Grossmann plays a different role.
Fitting Brunner in the team is a bit tricky. I think that Simpson's plan was to go with a Brunner - Romy - Hollenstein line, based on the fact that Romy was supposed to center the Hollenstein line before his injury, so replacing Bodenmann with Brunner could make sense, except that having i and Brunner on the ice together is a bit risky. He could play with Plüss, but that would mean dropping Moser, who is having a very good tournament. Maybe Bieber could be dropped and Moser could play with Trachsler and Walker? Or maybe on the Gardner line? Ambühl's skating it key to this line's defensive success, so Brunner would have to replace Suri, or maybe Gardner himself and have Ambühl playing center (by the way, I find it strange that it's Gardner and not Ambühl forechecking for this line, I would switch them).
Diaz for Blum does indeed make sence, even if you can't say anything bad about Blum's performance level until now.
Agree about the trickyness of shuffling Brunner into the Line-up without messing up this so well-balanced line-up.
Bodenmann just makes the perfect 3rd man for the i-line, letting the 2 others do most of the playmaking, and concentrate on finding shooting positions and crashing the net... though if needed he got the hands and smarts to support the other 2 with the "Tiki-Taki"-game. as you've written, with Brunner on this Line they could die in beauty...
so either taking Suri out or take Gardner out and do a complete rebuild of the other lines, maybe like this:
Brunner-Plüss/Walker-Suri
Niederreiter-Plüss/Walker-Moser
Bieber-Trachsler-Ambühl
about the Ambühl-Gardner issue:It's because of his 1-3-1 system where the C does control the opponent's puckholder into the trap...so he had to switch their positions and getting even worse in FOs... if Simpson is once forced to chance system, e.g. a double-forechecking,I'm sure we gonna see Ambühl flying again.