Shaker graduate Tommy Kahnle suffered his first major league loss on Wednesday, allowing a walk-off home run to Miguel Montero in the Colorado Rockies 5-4 loss to the Arizona Diamondbacks.

Montero’s homer led off the 10th inning and came after Rockies closer Rex Brothers squandered a 4-2 lead in the bottom of the ninth inning.

Kahnle is still having a fine rookie season though. He is now 2-1 with a 1.93 ERA. He has 13 strikeouts in 14 innings and has allowed opponents to hit just .188.