Save
Finishing a win while protecting a close lead.
What it actually is. Credit for finishing a win under specific conditions: a lead of three or fewer, or the tying run on deck, or three innings of finishing work.
What a scout reads off it. The save is the rare case of a statistic reshaping the sport rather than describing it. Once it existed, managers began saving their best reliever for the ninth inning with a lead, which is often not the highest-leverage moment of the game. Win probability added is the honest measure of what a reliever did.
Where the lines are. Forty saves is a full season as a closer on a good team. Mariano Rivera's 652 is the career record and Francisco Rodriguez's 62 in 2008 the single season one.
How it lies to you. A save with a three-run lead and nobody on is very close to a free one, and it counts the same as a one-run save with the bases loaded. The count on its own does not distinguish them.
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