The company can analyze the bid preferences through FLiCA. If they are going to release a multi class vacancy for upgrades, they can preview how it'll look. They'll be able to see about how many crews they'll be able to get voluntary into SEA, how junior upgrade will go, ETC. So it's very plausible that the CP knows exactly how junior it's going to go. They would be stupid not to be looking at this info.
Upgrade going very junior or even going to the street is a huge win for recruiting. If the next vacancy is a large one, encompassing all the upgrade classes for June, we may see new hires awarded captain. Remember, they said they wanted to upgrade 8 per week: 5 Tuesday's in June = 40 upgrades for June. Upgrade is currently 3 away from 11/2014 hires. 40 could most definitely take us into pilots who are still in training.