Here's how it always is.
Those that say "No" are usually young, less senior employees that follow rumors and social media. For example, that viral misunderstanding that the "pension is frozen". Usually young and less senior employees don't even have it on their mind but the minute its on social media then they feel as if they're at a loss. Similarly many people loved the pay jump initially but the minute the socialists and other groups said they deserve more, then they felt they were at a loss.
Those that say "Yes" believe in the contract and have the conviction that its good. They will vote. Those that follow social media and rumors tend not to vote.
With that being said, I believe it will pass with a large margin due to many people not voting at all.