Since 1957, there have been only 108 games in which the starting pitcher has earned a negative game score*. Five have occurred this year: Simontacchi (-2), Shields (-3), Feierabend (-4), C.Lewis (-6) and Jon Garland (-11).
The first thing that strikes me here is that in 50 years, there are 108 such games (about 2 a year), but this year we've already got 5, and we are not even 2/3 of the way through the season. The second thing is how bad that Garland score is. Tied for 7th worst in the last 50 years.
But we're going to have another one. Jason Jennings gave up 11 earned runs in the first inning of today's game against the Padres. Although not "officially" computed by Baseballreference.com yet, I've got him with a game score of -11, tying Garland for the worst this year.
That's 6, and counting. We're on pace for 9 of these things, which would represent almost 9% of the below zero game scores since 1957.
*The Bill James Game Score is really a toy to determine how dominant a starting pitcher is on a game-by-game basis. Every pitcher starts the game with 50 points. You add 1 point for each out recorded, and 2 points for each inning (or fractional inning) completed after the 4th. You also add 1 point for each strikeout. Then, subtract 1 point for each walk, 2 points for each hit and unearned run allowed and 4 points for each earned run allowed.
