The 33-year old Canadian international scored his 16th goal in his 32nd appearance for the campaign as DC forced a 1-1 draw with Spencer's Timbers and the former Chelsea man is adamant he saw this season's MVP in action in Washington.
"If [De Rosario] doesn't get MVP of the League there's something wrong," Spencer said. "Plain and simple.
"For the last three months of the season since he came here he's been the best player in the League by far - a country mile."
De Rosario has played for three clubs this season, commencing with Toronto FC - where he spent the previous two campaigns - before playing 13 times for New York Red Bulls and onto DC where he has netted 13 times in 17 outings.