Mittens don't give proper base stats

Mittens say they give +10 dodge and crit, with the spatula saying it give "an additional +10 dodge and crit". However, whoever I put it on has only 35% crit, 10 more than the base 25%. I can't see dodge, but I assume it likewise is only 10%, rather than the advertised 20%.

This is extremely consistent, rather than only happening in one game or on one champion. Please fix ASAP. =)