Hi willy - it doesn't look like a hustle to me. Pablo should be a perennial Cy Young contender, if he's properly managed. Of the pitchers you would give up, only Kirby is the true prize, and he's 2 or 3 seasons away from being relevant. And development is an uncertain process- 1 catastrophic injury, and Kirby's no longer a stud. Any deal that brings in a guy like Pablo is worth considering.
BUT— what's Pablo's contract status? (The window that opened up wouldn't show me.) If he's not under contract for next season, RUN AWAY from this deal, or counter with a deal that drops Kirby. Pablo Martin under long-term control is a fantastic asset. Pablo as a 1 season rental is a total screw job. If Pablo is in the last year of his contract, the other owner knows whether Pablo is willing to re-sign. If Pablo is unwilling, and the other owner wants to dump him on an unsuspecting newcomer, then you're getting screwed. If Pablo is willing to sign long-term, then the deal is worth considering, and I'd suggest going for all 5 seasons you can possibly sign a player for.
So I'd suggest keep negotiating. If there's any question about control over Pablo, walk away. Or agree to trade the 2 other players, but hold Kirby.
1 final alternative: if it's your first season, make no major trades and just get to know the world members and watch the talent develop. People who've been there longer have an intrinsic advantage, having watched players and seen multiple scouting reports. Patience is always the safest approach at the start, and unless the vet who proposed the trade is trying to swindle you, they should agree.