NHL guides are terrible. Half of Czech and Slovak accents are wrong there. My hypothesis is that the guides are all randomly generated by the Family Guy manatee.
The funny thing is that all Czech (and I am nearly certain all Slovak) names are extremely easy - the accent is ALWAYS on the FIRST syllable. (Incidentally, the signs above certain vowels that you can sometimes see are not accents - they just make the vowel sound longer).
Sekera has no special signs in his name, so he is indeed SEK-er-uh. And just FYI, that means "An axe" or "A hatchet".
And yes, Vokoun, Sykora, Beranek, Hrdina - those names have accents on the first syllable as well...