Sierra has the distinction of being a two time Yankee failure. He spent the end of 1995 and start of 1996 in the Bronx. He came back and played for the Yanks from 2003 to 2005.
In his first stint, Sierra played 152 games with the Yankees, hitting 18 homeruns, and hitting .259. He struck out 92 times.
His second stint was longer but worse. Desperate for power, the Yankees reacquired him in the middle of the 2003 season. In 231 more games for New York, he hit 25 homeruns, hit .249. He knocked in 125 runs.
Sierra wasn't a monumental failure like Jose Contreras or Jeff Weaver were. But the fact that the Yankees were so desperate that they got (and kept) a 37 year old over the hill slugger who couldn't hit for average just goes to show how sad the Yankees are this century.