This is Harrison Barnes of the Golden State Warriors. He's wearing a jersey with sleeves.
Why is he wearing a jersey with sleeves? BECAUSE SLEEVES ARE THE FUTURE!
On February 22nd against the San Antono Spurs, the Warriors will become the first NBA team in the modern era to wear a jersey with sleeves — and it may be the start of a new uniform trend. The jerseys, which Adidas calls the "adizero NBA short sleeve uniform system," are 26 percent lighter than current NBA jerseys (which are already very, very light). 60 percent of the jerseys are made from recycled material, according to the Mercury News. Adidas hopes the jerseys will catch on and eventually become the league standard.
Although NBA jerseys with sleeves look odd at first glance (and the Warriors will certainly look foolish playing a team without sleeves), more fans will likely be comfortable wearing around sleeved jerseys as a part of their daily life. Replicas will cost more than the current styles, though, with prices rising to $110 dollars per jersey.