The Mavericks began what might be a prolonged stretch without Maxi Kleber, and to those who don’t believe that’s a significant development, we offer a pair of rebuttals. Wednesday night in American Airlines Center: Cleveland 105, Dallas 90. Mavericks record this season without Kleber: 1-5. This season has illustrated that Dallas (14-14) has other issues, but without versatile 6-foot-10 forward…