Diaz, 32, batted .250 with a .302 on-base percentage, seven home runs and 31 RBIs in 84 games for Atlanta last season. His 2009 was far better, with a .313 average, .390 on-base percentage, 13 home runs and 58 RBIs. He is a career .301 hitter, topping out at those 13 home runs in 2009.
Looking at a platoon role, Diaz batted .273 vs. left-handers, .223 vs. right-handers in 2010. For his career, he bats .335 vs. left-handers.
Diaz became a free agent after being non-tendered by the Atlanta Braves. He has one year of arbitration eligibility left. This year he played in just 84 games due to an infected thumb.
Though the acquisition of Diaz addresses one need, the Pirates aren't done. General manager Neal Huntington acknowledged, too, that any additional moves may cost the team some prospects.
"We'll always look for upgrades and always look for ways to improve the club," Huntington said. "We've got to be smart about it, but it may come at the cost of prospects. There may come a time where it may come at the cost of a lot of prospects. At this point we're always looking for upgrades."
An upgrades at shortstop remains a possibility. Ronny Cedeno is slated to be the everyday starter in 2011, but the Pirates are known to be eying an improvement, and Jason Bartlett, Brendan Ryan and J.J. Hardy are all available for the right return.