Guinn appeared in what would be the last four games of his career in 1971 for the Houston Astros, not factoring in a decision while pitching 4.2 innings of scoreless ball, collecting one save.
It was a comeback of sorts since he played all of 1970 in the Minor Leagues, mainly as a starter for the Oklahoma City 89ers in Double-A ball.
1969 saw him see the most action of his career when he appeared in 28 games for Houston, going 1-2 with a bloated 6.67 ERA over 27 innings pitched, all out of the bullpen, with 33 strikeouts and 21 walks.
Before that, he played the first three games of his MLB career in 1968 with the team that drafted him, the Atlanta Braves, throwing five innings and giving up two earned runs for an ERA of 3.60.
All told, Guinn’s career numbers were a record of 1-2 over 35 appearances, with an ERA of 5.40 in 36.2 innings pitched, with 40 strikeouts and 27 walks.