Weird thing is we don't really know when these deals were actually completed. I think Nico's was done before today and they delayed announcing until after the Opening Day game so as to not distract from the game/festivities. Other deals could possibly be done as well and they're slow-rolling them, who knows.
I love me some Happ, but if I were to choose I go with Seiya on an extension, we need to slug and I think he still has a bit of upside, I think he can have a 4 WAR year in him if healthy, avoids the usual extended slump, and plays RF all year over DH.