I can't remember if you're a Delta pilot or not. If you are, you should get your info from the road shows and not from people on the internet. Anything I tell you is second-hand info, so your best source of information isn't me. If you're not a Delta pilot, though, and are just curious, then this should suffice:
The old language was difficult to track and enforce. The MEC settled a grievance regarding it recently, in fact. So the first issue that had to be dealt with was making sure it was easy to track and enforce the language. Unenforceable language, no matter how many warm and fuzzy feelings it gives you, is worthless. So moving from EASKs to block-hours makes it far easier to track and enforce to make sure that the company is complying with what they've agreed to without a bunch of mathematical gymnastics. Furthermore, pilot jobs are always related to block-hours, not seat-miles (as long as you're looking at similar stage lengths, which we are here). So it makes a lot more sense to structure a scope provision around block-hours than it does around seat-miles or seat-kilometers.
So, with the new language, whether it's good or bad is dependent upon the gauge (size) of aircraft that both Delta and the JV partners are using, because EASKs factor in the number of seats carried. Right now Delta is using a smaller gauge on average than the partners. So let's say Delta decided to pull out some planes because the transatlantic market wasn't doing well. So Delta is now flying less flights, and less pilots are needed at Delta. With the current language, you just reduce the number of ASKs on the JV partners and they're good to go. Delta pilot jobs are reduced, but the JV partner hasn't had to reduce frequency. With the new language, though, if Delta pulls an airplane out of the market, which reduces block-hours, then the JV partners will have to do the same to keep the block-hour ratio in limits.
Of course, if you believe that the transatlantic market is going to grow significantly, then you're better off with the EASK language, because if a JV partner increases aircraft gauge without increasing the number of flights, then Delta would have to either increase gauge or increase frequency in order to keep the ratio within the limits.
So the language that you think is better is highly dependent on what you gamble the transatlantic market is going to do over the next few years. CNBC runs in my office around the clock, and I can tell you that all of the best financial minds in the world can't agree on such things, so any pilot who claims that he knows for sure is a liar. It's a gamble either way. So I would say it makes more sense to link the language to block-hours, which directly rather than indirectly affect pilot jobs, and is also much easier to track and enforce. But either way, it's nothing that is going to make a huge difference to pilot jobs, so getting all bent out of shape about it doesn't make a whole lot of sense. When you're planning to add 800+ pilot jobs per year, and you're bickering over the slight possibility of losing 100 jobs at some point in the future, you're just being stubborn. Furthermore, it's offset by the tighter limits on outsourced RJs, which is also important. So this is really not the big issue that the APC clowns would like you to believe.