It's The Bottom Of The Ninth Poem by John F. McCullagh

Father Time stood undefeated.
Bonds came close, but Barry Cheated.
Roger Clemens had a career for the ages
but oft fell prey to roid based rages.
Mariano Rivera was a more worthy foe
No pharmacological freak was Mo.
He threw one pitch, his control was fine,
and was smart enough to leave on Time.
I stood up and joined the cheers
the day Rivera last appeared
and, though I wept to see him go,
Time would never lay him low.
Mo Struck out Time, he had it cooking
A called third strike that left Time looking
like Beltran on another night
good morning, good Evening and Good NIGHT!