Celta Vigo is very lucky that Barcelona did not play with a winning mission in the last match which allowed them to win that kept them away from the relegation zone. The defeat in the last game did not have a big impact on Barcelona even though their winning record was tarnished, Barcelona played only to meet the requirements as a sign that the season was over. An additional three points allowed Celta Vigo to stay in La Liga next season. Real Valladolid, Espanyol and Elche were relegated to Laliga Smartbank.
this last match for Barcelona is a match that doesn't mean that it won't affect anything in its position which has reached the top of the standings and on the other hand I don't consider Barcelona's last performance that lost to Celta to be a bad thing because it doesn't really matter and it's just that Barcelona gives a chance to Celta to stay away from the relegation zone. so Celta should be grateful to Barcelona for trying to lose in their last game.
if we think logically it is actually very unlikely that Barcelona will lose to Celta but maybe this is the wise intention of the Barcelona team.