Diamondbacks trade Luke Weaver to Royals for Emmanuel Rivera

The Royals and Diamondbacks are nearing agreement on a deal that’ll send right-hander Luke Weaver to Kansas City for infielder Emmanuel Rivera, reports John Gambadoro of 98.7FM radio in Phoenix.

Weaver was once a high-profile acquisition of the Diamondbacks, coming over as part of the package they received for sending superstar Paul Goldschmidt to the Cardinals. After the first 12 starts he made for Arizona, it seemed like they had a rotation stalwart on their hands. Weaver put up a 2.94 ERA in 2019 with a 40.7% ground ball rate, 26.5% strikeout rate and 5.4% walk rate. Unfortunately, a forearm strain ended his season early and he hasn’t been quite the same since.

Weaver was healthy for the shortened 2020 campaign, making 12 starts and throwing 52 innings but putting up an ERA of 6.58 in that time. He was better in 2021, getting his ERA down to 4.25, but was limited to just 13 starts by a shoulder injury. Coming into this season, the D-backs moved him to the bullpen, which has led to results both encouraging and discouraging. His 7.71 ERA is certainly unappealing, though there are reasons to believe that isn’t a true reflection of his work. His 24.1% strikeout rate and 6.2% walk rate are both better than league average, and he’s also allowing just 7.7% of his fly balls to leave the yard. What seems to be hurting his ERA is an unsustainable .434 batting average on balls in play and a 55.9% strand rate.

Still, this is a sample of just 16 1/3 innings after multiple seasons of disappointing results. The Royals won’t have a ton of time to get Weaver back on track, as he is set to reach free agency after the 2023 campaign. He’s making a salary of $2.875M this year and is eligible for another pass through arbitration next year.

In exchange for Weaver, the Diamondbacks are getting Rivera, 26, a corner infielder who hasn’t hit much in the majors but has shown plenty of promise in the minors. Since making his MLB debut last year, he’s gotten into 92 games and hit .243/.294/.378 for a wRC+ of 87. However, in 63 Triple-A games last year, he hit .286/.348/.592 for a wRC+ of 144. In 20 games there this year, his line is .307/.388/.520, 142 wRC+.

Rivera is primarily a third baseman and would likely slot behind Josh Rojas on Arizona’s depth chart, though Rojas is capable of moving to other spots on the field if they really want to give Rivera a shot. Rivera’s also played some first base and could perhaps see some time there if the D-backs pull the trigger on a Christian Walker trade, as they have reportedly considered. However he’s deployed, Rivera comes with an extended window of control, having come into this season with less than a year of MLB service time. He also can be optioned for the remainder of this year as well as another season, potentially delaying his free agency and arbitration.

For the Royals, they likely felt Rivera was squeezed out due to their crowded corner infield mix, with Nicky Lopez getting a lot of playing time at third, while Vinnie Pasquantino, Nick Pratto and Hunter Dozier are also around for first base or corner outfield duty. The designated hitter slot is also a little busy between that group and the catching duo of Salvador Perez and M.J. Melendez. They’ve used that surplus of corner infield bats to add an intriguing arm, while the Diamondbacks have taken a pitcher they couldn’t get good results out of and turned him into a controllable infield depth option.