I am more commenting on the being "cautiously optimistic" part. There is no reason to be even slightly optimistic. The pitching is pretty good but you won't win unless you consistently score runs. The Mariners have been swinging the bats better but they always do this, it is all in the script.
They will go back to being the team that loses 2-1. 3-0, 4-2 etc. soon enough.
Looking more deeply into it, you're probably right. My thinking was 1) most of their year to date performances seem sustainable on an individual level and 2) on a team level their run differential is right in line with their record so they haven't been getting lucky by squeeking out fluky one run games.
What I failed to notice, and this discussion illuminates, is that the offense is getting real lucky when it comes to run scored. Their team OBP and OPS are not capable of sustaining a 17th place in runs scored. They are simply getting lucky with RISP, and we know that won't continue. They are going to fall back towards 23-27, and that regression is going to hurt.
I still think they're ultimately better than the team we've seen this far with Cano sure to hit for power at some point, Almonte 86'd and Iwakuma back, but those improvements will probably only make up for the luck they've had in runs scored so far.
I still like my over 8.5 wins in June, though.