Blackwood was drafted by the Oakland Athletics as a 16th round pick in the 2016 MLB Draft. Blackwood spent the majority of his season in A-ball with five appearances for the Vermont Lake Monsters and 13 appearances for the Beloit Snappers finishing with 25 strikeouts in 26.1 innings and a 2–2 record with a 3.26 ERA in his first pro season. He spent the full 2017 season with the High-A Stockton Ports where he held batters to a .205 average, made 19 saves in 20 opportunities, and struck 48 batters out compared to 18 walks. He finished the year with a 1–5 record and 3.00 ERA. He started the 2018 campaign with the Double-A Midland RockHounds in the Oakland organization
