Essay question for today: Did the knee injury save Mariano's life?

Here's one for the fate crowd (of which we are active members.)

Rivera doesn’t know whether the blood clot was there before he suffered his knee injury last Thursday, as he hadn’t experienced any pain or soreness in his calf prior to this week. Still, the closer acknowledged that the clot wouldn’t have been found if not for the ACL tear.
.Yep. There's a chance that it was already there, and that one day, in any kind of situation, the greatest closer - hell, the greatest Yankee? - in history could have been taken down by something nobody knew. It would be like a combination of Thurman Munson and Lou Gehrig. He wrecks his knee, he has tests, and they find it. Who knows?
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“Maybe it is a blessing; I always see it like that,” Rivera said. “I always say that things happen for a good reason.”