Well, the Horde fleet came into being at the start of the Second War (tides of darkness and all that) as a means of invading Lordaeron. When the fortunes of war turned against Orgrim, some of that fleet might have deserted or they could have gone with Gul’dan prior to all that in his hunt for the tomb of Sargeras.
By this point, whichever it might be, Dalazzar could be rather disillusioned with everything. The bloodshed winding down in defeat leaves the demon blood haze unfulfilled and either Gul’dan’s wicked ways or Orgrim’s defeat leaves much to be desired for an orc clinging to any honour.
Either way, he finds himself on the ocean whether that be as part of a crew or drifting on debris after a lost battle. It’s not unreasonable then to find his way to the cosmopolitan beacon of racial harmony that is the pirate den of Freehold where he and his crew get tangled up, split up or swept up in a bigger pirate crew.
Living free while dealing with blood withdrawal, he falls into mercenary work to get by and adopts proper fencing in addition to his old scout and seadog skills. No matter where this takes him in the service of the highest bidders, the sea always calls him home.
Some time after, he learns of Thrall and the establishing of Durotar as a home for free orcs in a new Horde. An opportunity to start anew coupled with a feeling that he “should have been there” has him travelling to Kalimdor if he wasn’t there already.
Now, looking at the timeline we find ourselves roughly 22 years since crossing into Azeroth from Draenor. If we assume Dalazzar started young in the First War, he became a warscout in his late teens as orcs are fit to fight rather young. By the start of Classic, he’s lived a life on the waves and is roughly in his 40’s, though he might be older.
As it’s time to make up for his wayward ways and help the orcs as a people, he lends his expertise to the New Horde and in Durotar’s new and ramshackle state, his naval expertise weighs heavier than any old resentment toward him as an oathbreaker.
By the start of things, he’s doing what he knows best to get by; scouting and sailing while occasionally called upon to show the whelps how to interpret naval charts, read the wind and so forth. In this, he is useful but unfulfilled, longing for the sea once more and he keeps hiding some gold like a proper pirate to one day buy his own ship.
