Conversation so far:
in regards to jason giambi, what was the colorado rockies about?
Looking for a veteran bat to help their playoff push, the Rockies agreed to a deal with Giambi on August 23, 2009.
was that successful?
On May 19, 2011, against the Philadelphia Phillies, Giambi hit three home runs in one game, the first such game for him of his career.
who did giambi play against that day?
the Philadelphia Phillies.
what were his stats during this time period?
CANNOTANSWER.
anything else about this time period I should know about?
Giambi became a free agent after the 2012 season.

Question: who were his clients?
Self-contained rewrite: who were Giambi's clients?