In return, the Athletics are receiving the No. 3 prospect in all of baseball - Leo De Vries (SS). Others heading to the Athletics include: SD No. 3 prospect Braden Nett (P), No. 13 prospect Henry Baez (P), and No. 17 prospect Eduarniel Nunez (P).
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Miller is tossing a 3.76 earned run average in 38 games this year, posting 59 strikeouts and 18 walks while giving up 16 earned runs on 21 hits in 38.1 innings. Opponents are batting just .163 off Miller this season. The 26-year-old Miller has 20 saves on 23 opportunities this season.
Spears is having a rough go at this year. The 29-year-old lefty is 7-9 in 22 starts with a 4.95 ERA. He's given up 61 runs on 112 hits in 111 innings, striking out 97 while walking 29. Opponents are hitting .258 against Spears this season - a career worst.
However, acquiring Spears may come from the team looking to move on from starting pitcher Dylan Cease in the coming hours.
Both Miller and Spears are currently on one-year deals and will be unrestricted free agents when the season ends.
Prospect Haul
For the Athletics, the 18-year-old De Vries is currently in High-A ball, slashing .245/.357/.410 on the year with 8 home runs, 46 RBI, and eight stolen bases through 82 games this season.
De Vries is the second-best shortstop prospect behind Konnor Griffin (Pittsburgh Pirates) and third overall behind pitcher Chase Burns, who is already on the Cincinnati Reds' roster.
Nett is tossing a 3.39 ERA in 17 starts this season while in Double-A with 86 strikeouts and 34 walks in 74.1 innings, giving up 28 earned runs on 71 hits. Opponents are batting .247 off the 24-year-old this season.
Baez is killing it in Double-A alongside Nett, posting a 1.96 ERA in 20 starts, giving up just 66 hits and 21 earned runs in 96.2 innings, striking out 89 while walking 31. Opponents are batting just .195 against the 22-year-old, who currently has a fantastic 1.00 WHIP.
Nunez has been automatic from the mound this year in the Padres minor-league system, tossing a combined 2.31 ERA through both Double-A and Triple-A. The 26-year-old has yet to allow a single run in 11 games in Triple-A this season, striking out 18 batters in 12.1 innings while allowing just two hits.