Astros trade for SS/3B Aledmys Diaz

New Astros utilityman, Aledmys Diaz - Mitchell Layton/Getty Images

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Weep, oh Jerusalem. The door is closed on a return to the Astros for Marwin Gonzalez.

Don’t weep. Expensive utility players aren’t a smart investment anyway. The real best option is to clone that utility player and pay him less. So that’s what the Astros did. Sort of.

Just a reminder of who Marwin Gonzalez has been for the last few years with the Astros: a multi-position player of indifferent defensive ability (ok, except at left field, where he was decent), with a nice amount of power that makes pitchers take him seriously, and below-average on-base percentages.

Today, as announced by Astros’ reporter Brian McTaggart on Twitter, the Astros traded minor league right-handed pitcher to the Blue Jays in exchange for major league infielder Aledmys Diaz.

This is a good trade.

Diaz, 28, holds a .275/.325/.458 batting line with 42 home runs and 11 stolen bases in three major league seasons with the Cardinals and Blue Jays. He has totalled 4.5 fWAR in 320 career major league games. For an apples-to-apples comparison, here is both Diaz’ and Gonzalez’ fWAR per 162 games for the last three seasons:

Diaz: 2.3 fWAR/162
Gonzalez: 2.3 fWAR/162

Well, that’s pretty nice. More on Diaz’ offense in a bit.

Defensive Comparison

By the publicly-available defensive metrics, and I’m primarily relying on Defensive Runs Saved and UZR/150, which is the defensive component of fWAR, Diaz also grades similarly to Gonzalez. Historically, Gonzalez has been a terrible infielder, hovering around 0 DRS at 2B and 3B, and well into the negative category as a shortstop. Diaz, too.

Diaz: -9.6 DRS per 1000 innings (-6.2 UZR/150)
Gonzalez: -11.3 DRS per 1000 innings (-6.9 UZR/150)

Diaz: 0 DRS/1000 (2.8 UZR/150)
Gonzalez: 3 DRS/1000 (-6.7 UZR/150)

At other positions, Diaz didn’t play enough to draw meaningful data, although he has played sprinklings of second base and left field over the past two seasons without raising any alarm bells.

So it’s fair to say that Diaz and Gonzalez are equivalent defensively.

Forward-Looking Offense

Over the last three seasons, Diaz has demonstrated a better ability to hit for power than Gonzalez. Diaz has a .183 isolated slugging score (ISO) compared with Gonzalez’ .177 during the last three seasons.

Diaz: 21.3
Gonzalez: 20

Diaz: 36
Gonzalez: 33

Diaz’ stats are largely propped up by a 2016 rookie season during which he batted .300/.369/510 for 132 wRC_ and looked like a legitimate star as St. Louis’ starting shortstop.

However, during 2017 his line dropped to .259/.290/.392 and didn’t recover in 2018, in which he batted .263/.303/.453.

This is where the ability to "look under the hood" comes in. Diaz’ 2017 BABIP was .282, and in 2018 it dropped all the way down to .269. Reminder that major league batters’ BABIP (or batting average on balls put into the field of play) should hover somewhere around .300, give or take. Contact oriented hitters with decent foot speed can typically manage BABIP 20 points higher than that, and the lumbering sluggers of the world can hover 20 points below.

The point is this: Those 2017 and 2018 BABIP’s are unusually low for a batter with a reasonable contact rate (Diaz’ is 81%, and Gonzalez’ was 78% over the last three seasons, for comparison), which could imply that he’s had his share of "bad luck" (or negative statistical influence, if you will). In other words, his true median level of performance might be closer to his 2016 rookie year (.312 BABIP) than his 2018.

To support this theory, smart people have developed "expected BABIP" stats based on contact percentages, ground ball rates, and a bunch of other things that are less influenced by opponent’s defense and the vagaries of randomness. You can find such stats at, among other places.

In 2018, Diaz’ xBABIP is calculated to be .296, and his xBABIP from 2017 was .314. Both of these numbers are a lot closer to his 2016 actual BABIP than his 2017 and 2018 ones were. Likewise, his 2016 BABIP and xBABIP are close, within 10 points of each other, lending more support to the "Diaz was unlucky" argument in his 2nd and 3rd seasons.

In 2018, based on his xBABIP, his batting line would translate to a very Gonzalez-like .283/.315/.411.

Smart money would bet that the Astros are gambling on a rebound on balls in play to help drive better performance moving forward.

To put icing on the cake, and also to support the "likely higher BABIP" theory, Diaz hits the ball pretty hard. Using the statcast leaderboard found at (all baseball fans should familiarize themselves with this, the greatest of current baseball websites), we find that Diaz ranked 98th in the major leagues with 6.0% barreled balls per plate appearance (Gonzalez = 162, with 4.5%). This ranking is one spot behind monster power hitter Miguel Sano, and only seven spots behind George Springer.

Diaz ranked 116th (three spots behind MVP candidate Alex Bregman) in hard-hit percentage; 39% of his batted balls are hit 95 mph or greater.

One should feel confident that a player who hits the ball so hard should be able to elevate his BABIP from so low below league average, and also continue the good power numbers.

A bit about Thornton

The Astros gave up Trent Thornton in this deal, a Triple A pitcher drafted in the 5th round of the 2015 draft.

Last season, Thornton posted a 4.42 ERA in Fresno, with a 4.01 FIP. He is fantastic at limiting walks, but projects to have a below-average major league strikeout rate.

At age 25, the Steamer projection system believes that Thornton could carry a 4.58 ERA in the major leagues in 2019.

An Astro for years?

Perhaps best of all, because of Diaz’ unusual contract situation, having come over from Cuba on a major league contract that expired in 2017 and was re-upped for 2018, Diaz has a whopping four years of team control left, meaning the Astros can hang on to him through 2022 if they wish. 2020 will be his first arbitration eligible season, according to

The Astros will be required to pay him no less than 20% less than his $2M 2018 salary for the 2019 season, but it is likely the club will simply re-up him at his current salary just as the Blue Jays did last season.

In summary…

The Astros gave up a minor league pitcher who appears to be a back-of-rotation starter or middle reliever, currently finished up with his second season at AAA.

In return, the Astros received a player who is arguably an upgrade over the dearly departed Marwin Gonzalez. Diaz can play (presumably) any infield position as well as left field in a pinch. He has more power than Gonzalez. He has nearly identical stat lines over the last three seasons.

Diaz appears to be a drop-in replacement for Gonzalez, with the hope of even slightly better offensive performance without a hit to defensive.

And the Astros can hang on to him for four more seasons.

One heck of a trade, showing that even without his top lieutenants, departed to bigger jobs at other clubs, Astros GM Jeff Luhnow can still add a lot of value and depth for minimal cost.