Daulton Compton Jefferies was originally signed by A’s scout Jermaine Clark…graduated from Buhach Colony (Atwater, CA ) HS in 2013…attended the University of California where he finished 15-13 with a 2.72 ERA in 37 games, 36 starts, in three seasons with the Bears…went 7-0 with a 1.08 ERA as a junior in 2016 but made just eight starts due to calf and shoulder injuries…was First Team All-Pac 12 as a sophomore.
Spent most of the season at Triple-A Las Vegas where he was 5-1 with a 4.91 ERA in 15 starts… also had two stints with Oakland and went 1-0 with a 3.60 ERA in five games, including one start, before his season ended on Sept. 18 when he was placed on the 10-day injured list with right elbow ulnar neuritis...Allowed a .208 opponents batting average with the A’s, which broke down to .185 (5-for-27) with a .661 OPS against right-handed hitters compared to .231 (6-for-26) with a .605 OPS against left-handers...Had a .296 opponents average with the bases empty, .115 with runners on base…opponents were 1-for-12 (.083) with runners in scoring position...Stranded all five of his inherited runners and first batters faced were 1-for-4 (.250) with a double...Tossed 5.0 innings in his start and more than 2.0 innings in three of his four relief appearances...His five wins with the Aviators were a minor league career high and he matched his best with 15 starts…also had career highs in ERA (4.91), opponents batting average (.288), hits (90), runs (44), earned runs (42), home runs (13) and walks (11)...Had a .316 opponents on-base percentage as he walked just 11 batters in 77.0 innings (1.29 per nine innings)…has walked just 23 batters in 176.1 career innings in the minors (1.17 per nine innings)...Struck out 68 for a strikeout-to-walk ratio of 6.18…has 189 career strikeouts for a strikeout to-walk ratio of 8.22...Based on a minimum of 75 innings pitched, he led Triple-A West pitchers in strikeout-to walk ratio, ranked second in fewest walks per nine innings, third in fewest pitches per inning (14.9), eighth in opponents on-base percentage and ninth in ERA...His opponents batting average broke down to .280 (44-for-157) with a .789 OPS against righthanded hitters compared to .297 (46-for-155) with a .830 OPS against left-handers....Allowed 23 of his 44 runs in the first two innings of a game for a 6.60 ERA…had a 3.83 ERA after that, including 1.93 in the third inning...Was 1-0 with a 3.58 ERA in five starts on four days rest, 4-1 with a 6.15 ERA in nine starts on five days rest or more...The Aviators were 4-5 in his no decisions and had a 9-6 (.600) record in his starting assignments…tossed six or more innings in seven of his 15 starts, allowed two runs or fewer eight times and walked one batter or fewer 12 times…had eight starts without a walk...Was rated as the A’s seventh-best prospect by Baseball America following the season...: Began the season on the Las Vegas injured list with right biceps tendinitis…was reinstated May 21 and tossed 4.0 scoreless innings in his Triple-A debut on May 24 against Salt Lake (7 h, 1 so)…had a no decision in an 8-5 loss…logged 4.1 scoreless innings and allowed just one hit in his second start on May 29 against Sacramento…was 1-0 with a 1.37 ERA and .225 opponents batting average over his first four starts through June 8…then allowed a career-high seven runs and issued a career-high three walks on June 14 against Reno but had a no decision in a 21-16 Aviators loss…surrendered three home runs in a game for the first time in his career…that began a four-start stretch where he went 1-1 with a 12.33 ERA and .408 opponents batting average…tossed a season-low 2.0 innings June 26 at Salt Lake… went 2-0 in five starts in June but had a 7.25 ERA, .323 opponents batting average and .969 OPS…struck out a career-high nine batters in 4.1 innings on July 3 against Sacramento but was charged with his only loss of the season…then went 1-0 with a 3.75 ERA over his next four starts before his first promotion to Oakland…allowed just one run in a career-high 7.0 innings on July 15 to defeat El Paso 5-1…matched his career high with nine strikeouts on July 20 against El Paso…allowed four runs on 10 hits in 5.0 innings July 26 against Salt Lake and was promoted to Oakland on Aug. 1…picked up his first Major League win that day in a start in the A’s 8-3 win at Los Angeles-AL (5.0 ip, 3 h, 3 r, 3 er, 3 bb, 3 so) but that would be his only outing before he was optioned back to Las Vegas Aug. 8…went 2-0 with a 4.00 ERA over his final three starts with the Aviators…logged 6.0 scoreless innings on Aug. 15 against Tacoma and tossed a career-high 96 pitches…yielded a career-high tying seven runs on a career-high 12 hits in 6.0 innings in his final start with Las Vegas on Aug. 20 against Albuquerque but had a no decision in a 12-7 win…was recalled by Oakland on Aug. 27 and compiled a 2.70 ERA and .222 opponents batting average in four relief appearances, all in A’s losses…pitched in relief for the first time in the majors on Sept. 1 at Detroit (1.0 ip, 2 h, 1 r, 2 so)…it would be his shortest outing as a reliever as he logged 2.1 scoreless innings Sept. 4 at Toronto, 3.1 innings Sept. 7 vs. Chicago (AL) and 3.1 scoreless innings Sept. 12 vs. Texas…was placed on the 10-day injured list Sept. 18 retroactive to Sept. 15 with right elbow ulnar neuritis and missed the remainder of the season.
Made his Major League debut after being added as the 29th man for the Sept. 12 doubleheader at Texas…started the first game and was the losing pitcher in the A’s 5-2 loss…allowed five runs on five hits and two walks in 2.0 innings…fanned Nick Solak in the first inning for his first ML strikeout…allowed five runs in the first inning on a three-run home run by Odor and a two-run home run by Guzman…then retired three of four batters in the second…was on the A’s Taxi Squad for each of the final two road trips of the regular season and the postseason…made one Spring Training appearance (0.2 ip, 3 h, 3 r, 3 er, 1 bb) before he was optioned to Triple-A Las Vegas March 6…was added to the A’s 60-man player pool June 29…was rated as the A’s number three prospect by Baseball America following the season.
Combined for a 2-2 record and a 3.42 ERA in 26 games, including 15 starts, with Single-A Stockton and Double-A Midland in his first full season following 2017 "Tommy John" surgery…struck out 93 batters in 79.0 innings, an average of 10.59 per nine innings…walked just 11 (1.25 per nine innings) for a strikeout-to-walk ratio of 10.3…was named the A's Organizational Pitcher of the Year…saw limited duty when he pitched, as he tossed exactly 3.0 innings in 24 of his 26 appearances…logged 3.1 innings and 3.2 innings in his other two outings…averaged 45.2 pitches per game…began the year with the Ports and was 1-0 with a 2.40 ERA in five games, three starts, when he was promoted to the RockHounds April 29…went 1-2 with a 3.66 ERA in 21 games, 12 starts, in his Double-A debut…combined with both clubs for a .242 opponents batting average, including .213 (31-for-145) against left-handed hitters compared to .268 (42-for-157) against right-handers…surrendered five of his eight home runs and issued seven of his nine walks to lefties…issued just one walk to batters leading off an inning…compiled a 2.48 ERA in 19 games at night compared to a 6.00 ERA in seven day games…was 0-1 with a 2.36 ERA in his 15 starting assignments compared to 2-1 with a 4.86 ERA in 11 relief appearances…walked one batter or fewer in 25 of his 26 appearances…was rated as the A's number four prospect by Baseball America following the season.
MINORS: Was credited with the first win of his professional career on Opening Day when he tossed 3.0 scoreless innings of relief on April 4 against Rancho Cucamonga…pitched 3.0 scoreless innings in each of his final two appearances with Stockton on April 19 against Modesto and April 25 at Visalia…was promoted to Midland on April 29 and did not walk a batter in his first eight games (24.2 ip)…allowed five runs over his first three outings through May 12 (9.0 ip, 5.00 ERA)… then was tagged with the first loss of his career in a start on May 17 at Corpus Christi when he allowed one unearned run in 3.0 innings in the RockHounds 1-0 loss…that began a five-game stretch from May 17 to June 7 where he allowed just three runs, two earned, in 15.2 innings (1.15 ERA)…tossed a season-high 3.2 innings June 7 against Frisco…also struck out a career-high six batters, his first of four six-strikeout games in 2019…allowed season-highs in runs (5) and hits (6) June 13 at Springfield but then allowed one earned run in each of his next five appearances (3.00 ERA)…logged a season-high 66 pitches in 3.0 innings June 18 against Springfield…matched his season-highs by yielding five runs on six hits July 14 against Corpus Christi…then tossed 3.0 scoreless innings in back-to-back outings on July 19 at Tulsa and July 25 against Arkansas to begin a season-ending stretch where he posted a 2.50 ERA over his final six appearances…walked two batters July 25 against Arkansas, his first career outing with more than one walk…allowed two runs in 3.0 innings of relief Aug. 15 at Amarillo for his second win…went on the injured list the next day with a right pectoral muscle strain and missed the remainder of the season.