Donna Vekic hires former Kerber coach

Tennis is hardly the only sport that subscribes to the “proven commodity” theory.

But the old theory has proven true once again.

If you coach one top player who produces results, you’re often not going to have too much trouble getting another good gig when that one inevitably ends.

And so, less than two weeks after Torben Beltz parted ways with former No. 1 Angelique Kerber, Croatia’s Donna Vekic announced Wednesday that she would be working with the German for the 2018 season.

“The next season is nearly upon us and I can’t wait to start working with Torben Beltz as my new coach. 2017 was one my best years so far on the tour as I broke the Top 50 and I won my second WTA title, I am eager to do even better with Torben. It’s a great opportunity to learn from one of the best coaches and I look forward to this new collaboration,” Vekic said in a statement from her management on her Facebook page.

Kerber already is working with Wim Fissette, who parted ways with Johanna Konta after a hugely successful 2017. Fissette was let go by Simona Halep after she also had a great season in 2014.

“I am very excited to work with Donna, she has a lot of potential and I am sure we can achieve good results together,” was the statement from Beltz.

Coaching musical chairs

Fissette worked with Victoria Azarenka from February 2015 to the end of July 2016.

And she, too, must embark on a coaching search after her collaboration with Michael Joyce officially ended last week.

Joyce signed on with the Belarussian, leaving a lucrative and secure gig with American Jessica Pegula, with the idea he could help the more accomplished Azarenka get back to the top of the game.

The former Grand Slam champion and No. 1 took time away to have son Leo. She returned during the grass-court season this year.

But Azarenka’s well-documented custody issues have kept her off the court since Wimbledon. And with no firm return date as the case continues to wind its way through the courts, Joyce had to make a call.

He is reportedly close to an agreement to coach … Konta.

The holdup – as so often is the case, especially with the women – so far has been the financials.