How does anyone get a psychological boost from being left in long enough to get hit around? He was up 6-0, in line for a win, coming off 42 pitches just three days prior, it was April 1st. And literally the last two batters he faced were liner to short, and liner to first. They took him out because he could go to the showers knowing that he pitched six very strong innings and was in line for the win. That was the psychological boost, not leaving him out there gassed to give up a bunch of hits and runs.
Right now Hays is my favorite player on the team. I like his enthusiasm and all-out style of play. It has its downside viz. exposure to injuries, but it’s fun to watch players who play like their hair is on fire.
In terms of what he can be offensively, I think Jones is a pretty good upper limit and aspiration, unless and until Hays is able to refine his plate discipline in a way that Jones was never able to do. To be fair, Hays has a 6.8% walk rate compared to Jones’ career 4.5%. But, I think to be as good or better than Jones offensively, Hays will need to get his walk rate in the 8-9% range at least, and get his outside of the zone swing percentage under 35% (he’s at 37.7% for his career, Jones was 41.5%, league average is 30.6%).
Hays should have good power but I think he’s a little short of Jones in that department.
My expectation is for Hays and Santander to remain healthy and avoid the DL (or whatever it's called). That should go a long way to having a successful season for each of them. With that said, I'd be thrilled if Santander hit .250 with 30 homers and 100 RBI, with Hays hitting .270, 25 homers and 80 RBI. But is that what I expect from them? Probably not. I think my lowest expectation would be for Santander to hit .240, 20 homers and 85 RBI, and Hays to hit .250, 15 homers and 70 RBI. Anything less than that would be disappointing to me... or if they spent a considerable amount of time injured.
Per Baseball Savant, Santander’s hard hit % was in the 38th percentile, so below average. https://baseballsavant.mlb.com/savant-player/anthony-santander-623993?stats=statcast-r-hitting-mlb
I think SG is fundamentally right that people should not put too much stock in stats accrued over 37 games. At the same time, like you I see Santander as a player who is still improving.