TAMPA, Fla. (AP) — New York Yankees' hitters involved in testing a ball that has undergone a factory rubbing at a factory have issues with the prototype's color."I was asked what I thought, and I thought it was too dark," outfielder Brett Gardner said. "The ball felt the same coming off the bat. I'd just like to see the ball be a little more of a white shade so it's a little easier for the hitters to see."The objective of the tests, conducted during spring training, is to develop a ball that eliminates the need for the umpires' room attendants to apply Delaware River mud mixed with water on about eight dozen new balls before each game. The goal is to improve the consistency of balls' performance.Major League Baseball is taking feedback from players and coaches, which will be incorporated into a later version. The commissioner's office has not yet considered whether the prototype could be tested in minor league or instructional games.Gardner, Gary Sanchez, Greg Bird and Miguel Andujar hit the balls during part of a recent pregame batting practice session. The balls have "PROTOTYPE" stamped on the sweet spot."A little dark," Sanchez said through a translator. "During BP, I felt like it jumped a little more than the current ball."The Yankees also were using standard MLB practice balls when the foursome hit.A 2019 spring training game ball used in a recent Yankees' home game that was rubbed by hand was noticeably lighter in color.Darkness of the balls used in games can vary from ballpark to ballpark.Bird agreed the prototype was too dark but thought the idea of a uniformed game ball is worth exploring.___More AP MLB: https://apnews.com/MLB and https://twitter.com/AP_Sports