Diaz struck out two in a scoreless ninth inning Sunday against the A's to earn his 15th save.
Diaz had little trouble protecting Seattle's 3-2 lead, bookending his outing with a pair of called strikeouts. The 22-year-old rookie has emerged as one of baseball's most reliable closers since taking over ninth-inning duties at the beginning of August, converting 15 of 16 save opportunities. He has a 2.30 ERA, 1.16 WHIP and a 15.9 K/9 rate in 43 innings.