Let's compare, shall we:
Besiktas 2016-17: Scored 24 in 47 in all comps. From December through February, 11 in 14 (one CL match in Ukraine, one EL match in Israel).
Besiktas 2015-16: Scored 17 in 43. Dec-Feb, 8 in 17. Only started the first two, and the final league matches, plus the Turkish cup.
Besiktas 2014-15: Scored 9 in 28. Dec-Feb, 6 in 8. Had a foot injury over the new year, so he missed half the possible games.
At least recently, the "can't cope with cold weather" is decidedly untrue.