Diaz leads all of baseball in batting average and leads all shortstops in Wins Above Replacement. He's great. Not sure why he's still hitting 8th everyday. Should be somewhere 3-5.
I feel like Hazelbaker and Piscotty are relatively interchangeable in the order. Neither of them is hot right now, unfortunately.
Gyorko is a really bad defender. Holy crap. And his bat usually isn't enough to make up for it (unlike Diaz).
Gyorko has the 3rd best batting average on the team (min 30 ABs) at .289. Behind Diaz and Molina. His OPS is 2nd behind just Diaz. He isn't a great defender but he can score some runs.
100% agree with you on Diaz. He should be starting everyday around the heart of the order until something changes. And hopefully nothing changes.