Ian Desmond is seeing a heavy dose of sliders this season. Last year, only 18.3% of the pitches he saw were sliders. He also leads the league in sliders seen in pitcher's counts at 34.5%.
Oddly enough, Desmond is hitting .269 off sliders this season, which is about 50 points higher than league average. Last season, he hit .222. And while that was slightly below league average, it wasn't enough to explain why pitcher's are going hard after Desmond with the pitch this season.
It's possible teams are taking into account Desmond's struggles against sliders prior to 2011. In his rookie season in 2010, Desmond hit just .165 against sliders, putting him in the bottom 16% of the league. He also posted a lowly .191 slugging percentage on sliders that year, good for 6th worst in the majors.
So far, Desmond has been doing better against sliders. However, he is still chasing them out of the zone at high rate (37.8% in 2011; 45.8% in 2012). While the results have improved, a high chase rate will eventually catch up to him. Unless he learns to lay off those sliders that miss the zone, pitchers will continue to throw the pitch and his numbers will more than likely decline.