It was the last match of FC Barcelona in 2012 and they did well. Messi scored one more goal to make his record more difficult to break for other players. To be honest, we may not see any player breaking this incredible record.
With this one goal against Valladolid, Messi took his number of goals in one calender year 91! Muller, Pele are now behind this Argentine international. Chances are good that Messi might score more goals in the next calender year because he has been doing better than last season. Good luck for Messi.