Delta expected ALPA to negotiate for higher rates on the E190s. ALPA had higher priorites, and basically said, good luck trying to hire onto an E190 with below-market rates.
It was an odd situation where the company basically would have had to use its own negotiating captial to obtain a higher 190 rate. They decided it wasn't worthwhile, and instead focused on/plussed up the order for what become A220s