David Ortiz, or "Big Papi," is a well-known cornerstone in the Red Sox organization. When he began his career with the Twins, he was no where near as threatening in the batter's box.
Whether it just wasn't a good atmosphere with Ortiz or if it was the coaching style here at the time (which is what I think), Ortiz batted .266 in 455 games with Minnesota while hitting 58 home runs in 1,477 at bats--an average of 25.47 AB per home run. Ortiz never batted in more than 75 RBI in a season while with the Twins.
When Big Papi arrived in Boston in 2003, he had a break out year with 31 home runs, 101 RBI and a .288 batting average. New coach, new batter. Since going to the Red Sox, he averages 108 RBI per season along with 34 home runs a year.
In 1377 games with Boston, Ortiz has an average of .290, 1088 RBI and 343 home runs in 5,062 AB--an average of 14.76 AB per home run.
Accolades since leaving Twins: 2004-2007, 2011 Silver Slugger award winner, All-Star 2004-2008, 2010-2012, finished 2nd in MVP voting in 2005. World Series Champion 2004, 2007.
See Ortiz's full stats here.