League-wide, there were changes on the manufacturing front, as Majestic bought the exclusive rights for all MLB teams. Several teams, the Diamondbacks included, were already under contract with Majestic, so there was no real change. The only noticeable difference was on the vests, as a Majestic logo was now placed on the left shoulder. This was partly due to the fact that Nike had secured the exclusive right to make all official undershirts, meaning Majestic could no longer place their logo on the sleeves of undershirts.
No changes, other than the Majestic logo now appearing on the left shoulder. The vests seemed to be worn less often this season.
Batting practice jerseys were worn at home for one game, on the Forth of July. The team had worn them for two games on the road and won both (see below), so they decided to continue with them upon returning home. They lost the next game, and the BP jerseys were not worn again. This game was the only time in team history that black jerseys have been worn with a purple hat in a regular season game.
With it being the Fourth of July, American Flag patches were also worn on the caps.
No changes, other than the Majestic logo.
The new Nike undershirts, for whatever reason, featured white stitching, no matter the color of the shirt. For most teams that wore sleeved jerseys, this made little difference, but it became quite noticeable with sleeveless vests.
The undershirts were also now available in a variety of materials, weights, and fits. Some players opted for a stretchy, tight material.
No changes to the black jerseys.
There was, however, a new wrinkle, as the team decided to wear their batting practice jerseys in a game on July 2nd at Los Angeles. Many teams had done this occasionally in years past, but this was the first time the Diamondbacks had ever worn a BP jersey during a regular season game. It seemed to work, as they beat the Dodgers 7-5. They wore them again on the 3rd and won again. Riding the winning streak, they returned home and wore them on July 4th, but lost that game and never wore them again.
No changes to the jerseys, other than being used in a regular season game. A new purple jacket was introduced, which many players chose to wear before games.
After Hurricane Katrina struck the Gulf Coast in late August, all MLB teams affixed American Red Cross stickers to their helmets as a sign of support. This was done on both home and road helmets, and they would be worn for the final month of the season.