The ratings just are a minor information, what matter is the other page, with the stats (man of the match, goals, assists..)
Right now you have 2 options, depending of how is performing your team and how much do you want this player, always in the case that you really need him..
or buy now at the beggininf of the season, or, save tokens and try to use resources to focus on other positions/players...
and if the DL already is a contributive player, I don't recommend to change him.