Indeed, this is the satisfactory model. Early crewed warp travel ought to be slow, be it because of poorly performing tech or conservative and cautious application of said. The less possible the Valiant trip, the better! After all, Kirk doesn't exclaim "Impossible!" every day...
The early warp probes might do better thanks to power allocation, since for some reason life support even in the 24th century is a significant resource, the shunting of which into propulsion can make a difference. Another possibility is that intense warp fields would be a danger to humans, or perceived as such, meaning that an automated probe would be the only type of starship allowed to go full throttle on the best tech of the day.
Yet further option is that small is fast - the entire Friendship One was supposed to fit aboard the Delta Flyer! And eventually did fit aboard the Voyager, and was never seen crowding the shuttlebay, say. Perhaps a two-meter craft can cross galaxies but anything large enough to accommodate a crew must putter along at much lower speeds? This would also be coincidentally consistent with "The Emissary" and the superfast torpedo taxi there.
Out of these options, the first two would help explain the Valiant while the third would not. If top speed is a mere matter of choice, the vessel might have jumped to high and seriously crew-endangering speed by accident. Indeed, Kirk's ship jumped to much-higher-than-maximum speed often enough, when commandeered by hostiles; Picard's did that once or twice, too. These vessels never traveled quite that fast by choice, not even when a lot was at stake. Perhaps warp coils are like that, a fairly basic coil theoretically already catering for infinite speed and not even requiring a great deal of power for attaining that? This in turn would be consistent with "Threshold"... And indeed whenever frighteningly high speeds are attained, some other part of the starship is the failure point, while the propulsion system happily drives the ship towards the impending doom.
So the "jammed engine" theory is fine for explaining the Valiant. It's just that so many other options exist. And we know that spacecraft operating in the vicinity of Earth in the 20th-21st centuries frequently faced abduction or other propelling to distant parts of the galaxy, even if our heroes before the 24th century may not have fully appreciated that.
In a nutshell, an unlikely premise in "Where No Man" is not a faulty one - unlikely is actually in the specs and highly desirable, both from the perspective of the premise itself (the heroes agree that the Valiant "should" not have happened), and in the greater Trek context (weird is the well-established norm).
Timo Saloniemi
