I'm still trying to learn DxO, I found that I don't like the results of many of the presets, so when I process a batch of images I will import the images with no corrections applied, make what ever corrections I want to the first image, cut and paste the corrections to the rest of the images and fine tune from there, Has I go along if a find a set of settings that work well with a type of image, i save the settings has a preset.
most users on the forums say the builtin presets are pretty poor.
David, on the DxO forums one of the main posters, Andy_F (he also handles email support for DxO) has made a set of presets. although he uses a nikon.
if you have some spare time
could you try Andy_F's presets and see if they are better for alpha then DxO presets? Since I don't really know what I'm looking at