A few thoughts...
1) Miller is a good, not great, prospect who has consistently at every MiLB level produced about 30% higher than league average. Nothing he has done has done has stuck out. He doesn't do anything particularly well, but doesn't do anything badly...which means as a prospect he is kinda boring...lol. (Thats not meant as a knock.)
He doesn't look like a starter on a MLB team, but perhaps one of those players that hang around as a util guy for four or five years, until he's due to make big bucks...maybe bouncing from org to org as a fringe 40 man player.
He and Clement are the two oldest of our MIF prospects, which is why they were the first ones here...not counting Gimenez...but I don't think anybody envisions either as the most likely to be a starter at any position over some other youngster we have. They are kinda the stop gap prospects until the others arrive.
2) Based upon a lot of inside evaluation over a long period of time..and not on six weeks of spring training...I think the FO and Tito envisioned last winter that TMac and Quantril were the best options for the back end of our rotation. The mega mirage of Logan changed their minds.
In the end, it appears that the original prognosis was correct. As is often the case, Spring Training means sh*t.
3) Speaking of mirages...Zimmer is living on a .400 BABIP, nine HBPs, and 22% of his hits haven't left the infield, none of which are sustainable. And he Ks at a 35% rate.
45% of his plate appearances result in a K, a HBP, or an inf hit. The two good results in that trio are unsustainable, unless Zimmer has turned into a combo of Brandon Guyer and Super Kenny Lofton. Zimmers HBP this season is close to Guyers career mark. His inf hit % is nearly double Loftons best season number.
But he is sure fun to watch run and play defense. However, if its possible to sell high, do it.
4) IMO, Mercados problem is confidence. It shows up in his speech, in his body language, and on the field. He has the tools to play this game well, but maybe not the mental toughness. In this he resembles Jhonny Peralta, who was either REALLY good or REALLY bad. Playing in Cleveland after Omar may have been the worst thing for him, and leaving Cleveland the best.
5) The org has to make decisions on Harold, Zimmer, and Mercado soon. One of them will probably stick as a fourth OF. Hopefully, none are being looked at as anything more than that, even a platoon bat. None of them has a split that screams lefty or right killer.
In my mind, its like the end of Boy Named Sue...Bill or George, anything but these three.