Tyler Green, 1995
We're talking about "one-year wonders" here, but how about "half-year wonders?" Because Tyler Green fits that bill. Green was originally drafted in the third round by the Reds out of high school in 1988, but he elected to go to Wichita State University rather than sign with them. It turned out to be a good decision, as it bumped his draft stock up so much that the Phillies took him 10th overall in 1991, ahead of such players who went later in the round like Manny Ramírez, Shawn Green, Cliff Floyd and, of course, Doug Glanville.
Green got a cup of coffee with the team during the magical 1993 season; then he spent all of 1994 at Triple-A. It wasn't a good year, as Green posted a ghastly 5.56 ERA with Scranton/Wilkes-Barre. It looked like he had "bust" written all over him. But then, for whatever reason, the Phillies decided to stick him in their rotation at the beginning of the late-starting 1995 season.
Green's first six starts were fairly shaky, but he shut out the Dodgers in late May and went on quite a heater for a while after. Beginning with the outing before the shutout, Green put together nine straight quality starts to run his record to 8-4 with a 2.81 ERA. His impressive run earned him an All-Star selection, where he managed to strike out Kirby Puckett as part of a scoreless inning. The stage was set for Green to follow up with a big second half, but it turned into an abject disaster.
In 12 appearances (11 starts) after the All-Star break, Green didn't win a single game, posting a 10.68 ERA over 44 2/3 innings. As a result of the implosion, his final line in 1995 showed an 8-9 record, a 5.31 ERA, and a 1.59 WHIP, one of the grizzliest season outputs that any All-Star has ever posted.
Worse still, Green was having arm troubles that led to him missing all of 1996. He'd go on to post poor results for the Phillies in 1997 and 1998, then never appeared in another major league game after undergoing multiple elbow and shoulder surgeries. At least we'll always have those five weeks in 1995 to look back on fondly.