Yeah, broadcasters mess up on names, but that's not the same thing. In Sekera's case, he actually changed his "official" pronunciation between Carolina and LA and then again in Edmonton. I have no idea what is close to the real pronunciation. But all hockey players have an official pronunciation. At the beginning of each season, each team has to call the NHL and read out the proper pronunciations, and then the NHL spells them as you see in the link, and the person who reads it out is supposed to confirm that the phonetic spelling is the one they expected, and then that's the pronunciation all the broadcasters etc. are supposed to use.

http://www.hockey-reference.com/friv/pronunciation-guide.html

You're somewhat dependent on how your GM (or whoever ends up making the call) does in reading them, and on the person at the NHL, but the pronunciations mostly stay consistent from year to year, right or wrong. The spelling key they use has a lot of limitations. I just heard a guy on the radio say that Jason Zucker's last name rhymes with looker, which I had not realized before, if true.