Aaron Gordon's streak is 40 games and he's 22 and he's starting and playing against starters unlike Mirotic. Mirotic is 27 in 1 week. It's much more reasonable to expect big jumps from players in their early 20s than of ones in their mid-late 20s. That's why I would say I'm more likely to buy into Gordon's improvement.
And, yes, I still would like to see Gordon over more extended period of time before I pronounce him the next big thing.
They are also very different type of prospect, which was reflected by where they were drafted.