Perhaps, the majority of Alves's crosses last season came in the second half of the season, making it more noticeable when he messed up?
Could be.
Further analysis of the stats
--Year---Accurate crosses per game---Crosses accurate/total---Total crosses per game---Eficiency--
13/14 ---------1.1---------------------------31/160------------------5.9-----------------0.19
12/13 ---------1.5---------------------------44/160------------------5.5-----------------0.28
11/12 ---------1.1---------------------------36/122------------------3.7-----------------0.30
10/11 ----------1----------------------------36/167------------------4.7-----------------0.22
09/10 ---------1.6---------------------------46/195------------------6.7-----------------0.24
So basically in 13/14 Alves had the second highest cross per game total of his last 5 season, but had the lowest amount of accurate crosses and the lowest crossing efficiency.
Btw, again, these stats are only for La Liga.