By Alek Arend One of Patrick Mahomes’s best qualities as an NFL quarterback is his ability to stay cool under pressure. But frustrations boiled over during the closing moments of the Chiefs’ 20-17 loss to the Buffalo Bills Sunday night. Mahomes had to be restrained by multiple Chiefs teammates during the closing moments. He appeared to be screaming at a nearby sideline official. We now know why he was so upset, thanks to the Chiefs. The Chiefs explained that Mahomes was furious about the offsides penalty on Kadarius Toney that wiped Travis Kelce’s impromptu trick play, which resulted in a touc…