Rangers RHP Kumar Rocker is all set to make his debut Thursday against the Mariners. Arms don’t always come back from reconstructive elbow surgeries, but Rocker has returned looking like the best version of what we dreamed he could be, wiping hitters away with superb command of an 80-grade slider that mixes well with his fastball and changeup. It’s a tip-of-the-iceberg type feeling at the moment as it stands to reason that there’s more in the tank for Rocker both this year and in the near future considering he’s just 26.2 innings into this healthy phase of career. In two Triple-A starts, he struck out 51.4 percent of the hitters he faced, walking 2.9 percent. That’s pretty good over any sample size.