For some reason, Klingon material in the novels gets a rather "reverential" treatment: much of the modern stuff in there is based very solidly on what has been told in the episodes and movies, and only very carefully and timidly explores beyond, never daring to contradict. Much of the older stuff in turn remains true to the FASA RPG and the classic novel
Final Reflection, in both of which John M. Ford used the TOS Klingons as the basis, sprinkled in a rationalization for the TMP Klingon look, and eventually added some characterizations from ST3:TSfS, too.
Basically, we know from "canon" that Klingons have the following ranks:
http://memory-alpha.org/en/wiki/Klingon_ranks
(Nitpicker's note: the rank of "Sergeant" is gleaned from end credits of ST3 only, and never mentioned or otherwise indicated on screen...)
Modern novels follow that to the hilt. Since most Klingon ground formations have been shown operating without much in the way of organization, we could well speculate that they are principally made up of
Bekk, or Warriors, and that the higher ranks are only involved in the "planning stages" and do not actively try to lead the rampaging formations. Thus, Klingons wouldn't really have anything akin to Sergeants, or at least the rank system within the
Bekk category would be very loose and always subject to challenges and change.
That sounds like yer typical medieval army, really: the noblemen (the officers) are careful about their rank and position, and well organized, but the actual cannonfodder fighters are disorganized rabble, with just a few elite units thrown in.
Also, the rank system for the noblemen would probably be top-heavy, as every House would participate by sending its own officers and men and ships, and every fighting House of any worth would probably warrant a General of its own. There could be Generals commanding 500 men, and Generals commanding 50,000 or 500,000.
Perhaps only the wealthiest Houses operate significant numbers of ships, and thus give rise to Admirals, whereas most Houses supply ground warriors, and thus sponsor Generals? That could explain the seeming imbalance in "navy" and "army" ranks: there are indeed two separate rank systems, but the "navy" is practically subservient to the "army" and mainly moves the latter to the battlefields - again in medieval style. In that style, the "army" would play a major role in shipboard fighting as well, and only the top officers of the ship, plus the few sailors needed for moving the highly automated vessels, would be "navy".
Speculation upon speculation there... The novels don't explicate, nor do they explore or experiment much.
Timo Saloniemi