Image via YouTube

Derby, Team Bat Dog for the double-A Trenton Thunder, has died of cancer at nine years old. Derby was a beloved member of the Thunder, and he began his retrieving apprenticeship in 2008 under his father Chase. Even as his face got all gray, Derby continued to do his thing and go pick up bats. Thunder GM Jeff Hurley announced Derby’s death Monday:

“Derby was one of the biggest parts of our identity in the nine years of his life and it breaks my heart to share this news with our fans ahead of our 25th season. His presence at our games and in the community was massive and every person and dog that interacted with him will miss him dearly.”

In his time with the Thunder, Derby has retrieved bats for Yankees players like Alex Rodriguez and Aaron Judge. He comes from a baseball family, as his son Rookie and one of his brothers also practice the family profession. Derby became the full-time Bat Dog in 2010, and spent last season working alongside Rookie, though their time together was not without incident.

Here’s Derby in action last season.

A true master of his craft. The Thunder announced that the Jan. 26, which would have been Derby’s 10th birthday, will now be Derby Day.