Pro Football Focus takes a look at the number of first downs and TDs allowed by cornerbacks last year. Robinson allowed 9 TDs in his coverage last year (1st) and 45 First downs and TDs combined (Co-2nd). Given his number of snaps it's not as bad as it looks but it's still bad as he allowed a first down or TD on 7,27% of his snaps (16th).
I believe that he is capable of doing better and that he really suffered from Spags' scheme. Nonetheless it is still worrying and he, along with the other DBs, will need to step up his game if we don't want to set new records next year.