Let’s start with Diaz: he’s 28, in his prime, and he’s good at baseball, producing 4.5 WAR over three seasons, including 1.6 last year when he hit 18 HR while playing middle IF. He can essentially play 3b/ss/2b, and we have no back up who can do that competently. Have I mentioned he can hit? His WAR last year matched dearly departed Marwin’s, but it took Marwin an extra 100 PAs to get there.
There was a scenario in which the Astros replaced Marwin with.... nobody. Kemp and Gurriel could sub at 2b, Bregman could sub at SS, and Gurriel could sub at 3b. Meanwhile, Tyler White can play the corners. That scenario made Astro Nation nervous, and apparently it made Luhnow nervous as well. So now we have a very good player to essentially be Marwin minus the outfielding. He’s even the same height, so it’s not impossible that he gets an occasional start at 1b. What’s not to like?
Plenty, I say, due to roster construction and option years. The Astros have a stable of both pitchers and hitters who are good enough to be rostered by about 26 other teams, but can’t crack the big league team in Houston. Key contributors to the 2018 success like Tony Kemp and Tyler White started last season in Fresno, where the Astros have stashed MLB talent for years, reversing the trend of stashing AAA talent in Houston, as the Astros did from 2011-2013. Marisnick took some time there last year as well. What’s so bad about a regular shuttle between Fresno and Houston, especially when the team is soon moving to Round Rock?
MLB has rules to prevent stashing players. They aren’t the strictest rules, but they are rules, like time to service before being exposed to the Rule 5 draft, and the number of “options” a player has. The Astros traded Thornton because there was no room for him on the 40 man, but he was too good to left unprotected. It happens to teams with tons of depth, and it will keep Thornton from being “Rogelio’d”. Good for him, if not necessarily good for us.
According to MLB DOT COM, a player on the 40 man roster has three “options” (http://m.mlb.com/glossary/transactions/minor-league-options). This means that a player can be “optioned” to the minor leagues three times without being subject to waivers. An option lasts an entire year. So essentially, there are three seasons in which a player can be optioned and brought back by the team, as many times as the team wants during that season. Players with more than five years must consent to being optioned.
Here’s the players on the cusp of making the roster currently constructed, and how many options remain: Kemp (0), White (0), Stasi (0), Marisnick (1). This reality is a construct of the MLB team being really good, and these guys not always playing at a level that would keep them on the team. Things get tricky going into 2019. If White is the starting DH, and AJ goes with 3 bench players, like last year, one slot belongs to Diaz, and another to Stasi or Stubbs. (Keep in mind, if they don’t want Stasi as backup, he would have to pass through waivers). In this construct, there’s one roster spot left for a 4th OF (assuming they either sign a LF or make Tucker the opening day starter). It’s either Kemp or Jake, and if they decide they want Jake, Kemp cannot be optioned without going through waivers. Similarly, if they aren’t comfortable with White as opening day DH, they can’t stash him in AAA. Unlike last year, when a guy like Kemp or White played well enough to make the opening day roster, but had to go to Fresno, this year they need to pass through waivers. Stasi did so last year, but he’s coming off a year where he produced 1.2 WAR in limited time.
None of this is science, just basic math. If the Astros think they have something in Myles Straw (Jake’s D and base running MINUS Jake’s power and K’s) and JD Davis (White’s power + better defense - White’s hitting for average), I would not be shocked if the Astros move White and/or Jake + Kemp this winter, especially if they’re thinking of adding a bat. Davis has two option years and Straw three. The point here is that the Astros can’t make a strict baseball decision. And if that doesn’t sit right with you, keep in mind that the decision was already baked into the Diaz trade.