By Jon Wertheim Also in this week’s mailbag: a discussion of Maria Sakkari’s oscillating career and a consideration of the height of chair umpires’s seats. A grab-bag mailbag this week while marveling over Alycia Parks… MailbagHello, Mr. Wertheim, With the increasing use of electronic line calling, do you think chair umpires still need to be sat upon a laddered perch? I understand they need a heightened vantage point to oversee all lines and corners of the court, but when courts are linespeople-free and calls are automated, is there still a reason the ump needs to climb to her seat? Also, umps…