One caveat: he said this was a rotisserie league. Doesn't roto have a built in innings limit? If you go the route of the inning flood (that's what it's called where I'm from, popular vernacular and all that jazz
and are very aggressive with it, you could potentially hit the 1250 innings limit in a matter of months (2 or 3). Granted, by then you *may* have insurmountable leads in W's and K's, but because you've been starting the dregs of the wire, this most likely won't be the case.
From experience, this strategy works best from the draft on up. If you go into the season with the knowledge you're going in for the penny, in for the pound, then it would be best to draft almost all hitting for over half the draft, with a few closers thrown in for good measure. As it stands (your draft is already completed), this may not be the best strategy to employ. For sure, though, check to see if there is an innings limit.
There's nothing unethical about the strategy, but if it's a rotisserie league then it may not be very effective. Assuming, of course, that the league has a max IP over the course of a season. In essence, every team that hits that IP limit will end up finishing based on wins/IP, K/IP, saves/IP. You'll probably win saves, but won't do well in ERA or WHIP. Wins and Ks depend on who you get.
That doesn't mean it's not worth trying. It could be fun to seek out the scrub pitcher of the week who you think has a good matchup. And if you dominate enough in the hitting + saves and manage to finish middle of the pack in the other four categories you'd have a shot at winning a 5x5 12-team league. Here's how:
hitting points (1st in each category): 60 points
pitching points (1st in saves, 7th in two, 6th in two): 38 points
Total score: 98 points.
98 points gives you a very good shot at winning the league. Even if you average a 2nd place finish in all the hitting categories you still would score ~93 points. Throw in a dead last finish in ERA and WHIP and you end up around 83 points - still competitive in a close fought league.
If you are talking about H2H, there's still nothing unethical about the strategy. It's just kind of annoying to play against. You can usually beat the mediocre to average teams, but will have trouble against the best teams.
"The game has a cleanness. If you do a good job, the numbers say so. You don't have to ask anyone or play politics. You don't have to wait for the reviews." - Sandy Koufax