Granlund isn't a good player - he's a middle-six complementary winger on the downslide of his career - he's not going to move the needle this season and by the end of the year is more likely to be deserving of being waived (he won't be, but that's a different matter) than deserving of top-six minutes.
Couture is a top-six complementary center who is also on the downslide of his career, but who was a much better player at his peak and so has much further to fall. He doesn't drive play, he needs a good play driver on his wing, but right now we have maybe three play drivers in Hertl, maybe Eklund, and maybe Barabanov, but the latter two are a prospect (albeit an excellent one) and an older and now injured complementary winger who himself needs someone strong to help him create space.
These guys aren't going to make this team much better. Of course we will win some games, but that will be due to luck, not due to our own skill, because we are entirely and utterly bereft of breakout ability.