That's why I was thinking it might not be so terrible to allow Jump Up to be more powerful if it is going to be a trait. Look at Stand Firm. That's a Strength Trait that allows a player to never be pushed back and never have a dodge result in a turnover. That seems pretty powerful too. Probably why Agility teams can't get it anymore.
As for the current wording of the skill, it's just odd that other skills explicitly mention 'after an opposing player has declared a pass', 'made a dodge roll'. Dump-off says the player can make a quick pass when an opposing player declares a block at him, not just whenever an opposing player declares a block at anybody, or when any block is declared at all. Jump Up is the only skill/trait worded in such a vague manner that it never explicitly says whose action. IT may be obvious, but as the only exception, it draws attention.
As an aside, did anyone ever play the PC Bloodbowl game? Am I wrong or was a player with Jump Up in that allowed to stand up at the start of the team turn even if you didn't come back to them till later in that team turn (Perhaps that's just the way BB was in 2nd Ed or something). That wouldn't be such a bad addition to the trait either.