I don't think you understand how the cap works at the deadline. Cap hits are pro rated at the deadline so the players entire cap hit does not go against the new teams cap.

From NHL.com: https://www.nhl.com/news/trade-deadline-q-a/c-409700
The salary that is charged against a team's cap is the pro rated amount remaining of the
player's average yearly salary. For example, if a player has an average yearly salary of $2 million, the amount charged against the acquiring team's cap is the pro-rated amount remaining of $2 million.

This is calculated by dividing $2 million by the number of days in the season (186). The
amount ($10,753) is then multiplied by the number of days remaining in the season from the day the trade is made (42 days if trade is on Feb. 28) to ascertain the amount charged against the team's cap ($451,613)."

I assume this rule is in place to encourage trades. This allows the power within the league to change quicker and the league becomes more stable and even. Teams that are out of the playoff get picks and assets for UFA and those power teams give up future parts for a win now.

So basically any player traded at the deadline (Feb 28 or around there) will only have a cap hit to their new team of 22.6% of there full cap hit.
Vrbata: $226,000 cap hit for his entire contract.
Hanzal: $700,600 cap hit for his entire contract
Vanek: $587,600 cap hit for his entire contract
Jagr: $904,000 cap hit for his entire contract

So for all of the trades even with no retained salary the Hawks cap hit would go up $2,418,200.

Vrbata has 1.2 million in playoff bonuses. Beware of that. Some of the retained salaries are a bit ridiculous.