Dickey (13-12) scattered four hits and two walks while striking out eight. The knuckle-baller threw 75-of-101 pitches for strikes in the gem.
New York's Andy Pettitte (10-10) absorbed the loss despite yielding just one run on six hits over 6 2/3 innings. He walked two and fanned five.
The Yankees' playoff hopes suffered another blow with the defeat. They came into contest trailing American League wild card co-leaders Tampa and Texas by 2 1/2 games, with Baltimore and Cleveland ahead of them.