Unmount your SD card in Settings>Storage, remove it, and reboot. Use the tablet for a while (like a few days) without the SD card and see if the random reboots recur. If they don't, plug it back in again, and see if the reboots start again.
Boot into Safe Mode, which temporarily disables all 3rd party apps: Safe mode: Samsung Galaxy Tab 4 | T-Mobile Support. (I couldn't find steps specifically for the Tab Pro, so I'm assuming the steps for the Tab 4 are the same.) This might not be an effective troubleshooting method if the random reboots don't occur very often, because it's hard to expect anyone to use their tablet for several days in Safe Mode, thus being unable to access any of the 3rd party apps you installed.
Boot into Recovery Mode and wipe the cache partition, which doesn't erase any personal data. Follow the steps in this video, and make sure you select Wipe Cache Partition, and not Wipe Data/Factory Reset.