Nope. Klingberg had shown only one flashy season before he got his contract. So he didn't have any leverage.
Miro has ELC until 19-20. If there isn't any stepbacks and he will be as good as it seems to be he will get lot bigger contract than JK.
Considering that defenders usually are at their best later than forwards that contract extension will probably be really good for Stars.
But not a steal like Klingbergs.
Seth Jones got 6x5.4m
Ristolainen 6x5.4m
Ekblad 8x7.5m
Those give probably some guideline.
Heiskanen's ELC will slide to 2020-21 because he didn't play in the NHL this year. So there will be a 3 year NHL sample going into his next contract.