Reinhart spent 6 fruitless seasons in Buffalo. Fiala has not, and is reputed to be looking for a long term contract. If MN is going to make a deal his salary probably has to be included, as otherwise there is no chance that they can take on Eichel's cap hit. If the deal could've been done before the Seattle ED, then Dumba could've been part of the deal, but that ship has sailed.
At some point KA has to get actual good players, not just prospects. It's not like Fiala is old and washed up, or overpaid.