The skid mark clearly shows the LH wheels were locked up at the point it departed. As for it being "taxi speed" complete nonsense, 737 would just stop at 15KTS taxi speed. The turning circle is to the RHS of the runway and there is no need to turn left before turning right the 737 can easily do this, even 747 land at Trabzon. Boeing perf tools give 1956 M with AB3 F30 and 1792M AB3 F40 at 63Tonnes with Anti Ice. ( landing weight based on ZFW plus min fuel and 162 pax). Nose Wheel steering is a low speed regime and won't cause the brakes to lock, so that's a red herring. The sensations the PAX describe of "speeding up" may equate to when the AB were disarmed. Non-standard RW CL lighting can be confusing. Deep landing with heavy left foot after disarming AB seems most likely, sadly. Several Turkish websites commenting on the "company culture" of putting crews under pressure. Notwithstanding any of this, our sympathy is with the aviators and we must remember we are all human.