39: [1981, 27-32, 5th NL West/29-23, 3rd NL West]
By June 1981, the Giants were poised to go nowhere, but then they got good news. Well, okay, it was bad news. Baseball went out on strike, which resulted in a weird split-season format when the players came back in August.
The teams atop of their divisions in the first two and a half months of the season were declared the division winners of the first half, and they would take on the teams that won their respected divisions in the second half.
The Giants went 27-32 in the first half, which meant the Giants had a clean slate when baseball returned on August 10. They took full advantage of the two-month second half, but they fell three and a half games short of the Houston Astros and went 29-23.
If any of the winning seasons would be ranked the worst, it would be the one where there was no baseball for two months and where a completely idiotic playoff system gave the Trolley Dodgers an illegitimate world championship.
Doyle Alexander was a bright spot for the Giants that year with a 2.89 ERA in 152.1 innings pitched. He struck out just 77 batters, which is crazy to think about in this day and time where you have to strike out a batter an inning to be a starter.