What makes Olney's story great, to me, is the descriptiveness of the writing.
The anecdotes used and the simplicity and clarity of the explanations were terrific and make the story one that anyone -- not just, say, a sports writer, or a pitching coach or a saber-metrics or physics expert -- could read, understand and picture.
Couldn't you just imagine Klesko's teammates snickering at him in the dugout -- not in any real derision, but at the comical-ness of a player like him whiffing so badly and repeatedly. And didn't you smile, too? I could, and did.
That sort of easy, relatable writing continued throughout. From a player "protecting" his prized, better bats -- although I kind of wonder how he'd do with those "first-string" ones against Rivera -- from being broken by not using them, to another player who was thought to be finding a way to succeed against the cut fastball only to have him admit that, hey, I wasn't trying to do anything special, and that his hits were, basically, a matter of dumb luck, to another considering a walk to be a hit and being really happy with that outcome compared to what could happen, the writing is vivid and engaging.
And yet, this story is also actually an informative explainer.
Olney pulls it off without becoming too technical or being too in-depth or going too long, and that's a tough balancing act. In this respect, this story was a 10.
As for the sourcing, well, of course the story's well sourced, and that certainly helps add weight to what's written. But, I'd expect a story to be well-sourced if it's written by an experienced sports reporter and appearing in the New York Times.