Its not so much the total drops, as the % of drops. Clayton (for instance) gets fewer looks (therefore) and needs to make them count. He doesnt (or I guess didnt) have the luxury of dropped passes.
Galloway: 102 passes thrown, 734 yrds, 5 TDs, 43% catch%
Clayton: 65 passes thrown, 360 yrds, 1 TD, 51% catch%