PHOENIX — Major League Baseball intends to push forward with the process that could lead to possible rule changes involving the strike zone, installation of pitch clocks and limits on trips to the pitcher’s mound.

While baseball Commissioner Rob Manfred expressed hope the ongoing process would lead to an agreement, he said clubs would reserve the right to act unilaterally, consistent with the rule-change provision of the sport’s labor contract.

Union head Tony Clark said last weekend he did not foresee players agreeing to proposed changes for 2017. Under baseball’s collective bargaining agreement, management can alter playing rules only with agreement from the union – unless it gives one year notice. With the one year of notice, management can make changes on its own.

“Unfortunately it now appears that there really won’t be any meaningful change for the 2017 season due to a lack of cooperation from the MLBPA,” Manfred said Tuesday.

MLB has studied whether to restore the lower edge of the strike zone from just beneath the kneecap to its pre-1996 level – at the top of the kneecap. Management would like to install 20-second pitch clocks in an attempt to speed the pace of play.

Players also have been against limiting mound meetings. The least controversial change appears to be allowing a team to call for an intentional walk without the pitcher having to throw pitches. In addition, MLB likely can alter some video review rules without the union’s agreement – such as shortening the time a manager has to call for a review.

Manfred said starting runners on second base in extra innings sounds unlikely to be implemented in the majors.

NATIONALS: All-Star catcher Matt Wieters and Washington agreed in principle on a $10.5 million contract for 2017, pending a physical, according to a person familiar with the deal. Wieters has played his entire career in the AL with the Orioles after being taken with the No. 5 pick in the 2007 amateur draft.

JIM JOYCE has joined John Hirschbeck, Tim Welke and Bob Davidson in retiring from Major League Baseball’s umpire staff.

Adam Hamari, Pat Hoberg, Gabe Morales and Carlos Torres have been promoted to the full-time staff.