Why wasn't Mo credited with a save?

Mariano Rivera's appearance on Thursday vs. the Orioles wasn't scored a a save, but instead a win.

Confused? Here is a thorough explanation from ESPN Stats & Info's Ryan Feldman:

Mariano Rivera entered the game on Thursday in the 9th inning with the Yankees leading 6-5 against the Orioles. An obvious save situation, right? Wrong. Rivera closed out the game without relinquishing the lead but was given credit for the win because the official scorekeeper decided that the pitcher of record -- David Robertson -- was ineffective in the 8th inning (entered the game up 5-2, allowed 3 runs on 4 hits to tie the game).

This is rare but there are some precedents. In the last 25 seasons, three other relievers (the Orioles' Chris Ray in 2006, the Angels' Shigetoshi Hasegawa in 2001 and the Mets' Armando Benitez in 2000 ) had entered with a chance to get a save, but were given wins instead, according to Elias.

Here's the rule on why Rivera was credited with the win:

Rule 10.17 (c)

The official scorer shall not credit as the winning pitcher a relief pitcher who is

ineffective in a brief appearance, when at least one succeeding relief pitcher pitches

effectively in helping his team maintain its lead. In such a case, the official scorer

shall credit as the winning pitcher the succeeding relief pitcher who was most

effective, in the judgment of the official scorer.

In case you're wondering, here's why Rivera wasn't also credited with the save along with the win:

Rule 10.19

The official scorer shall credit a pitcher with a save when such pitcher meets all

four of the following conditions:

(a) He is the finishing pitcher in a game won by his team;

(b) He is not the winning pitcher;

(c) He is credited with at least 1/3 of an inning pitched; and

(d) He satisfies one of the following conditions:

(1) He enters the game with a lead of no more than three runs and pitches for at

least one inning;

(2) He enters the game, regardless of the count, with the potential tying run either

on base, or at bat or on deck (that is, the potential tying run is either already

on base or is one of the first two batters he faces); or

(3) He pitches for at least three innings.

**Please note that there’s always an outside chance MLB could overturn the scoring decision, but the official scorer made a decision and as of now Rivera has been credited with the win.