Through one week’s worth of games, the Mariners bullpen is the leading source of heartburn in the Pacific Northwest. The vacuum left by Edwin Díaz will take many Jarred Kelenic doubles and Justin Dunn strikeouts to fill, but for now we have a mishmash of prospects and misfits to slam the door. Seattle’s surprising start has been made possible by a few strong starts in the ‘pen. Matt Festa has had three impeccable outings, Roenis Elías has emerged with 95-96 and a nifty changeup supplanting his picturesque curve, and Tuesday night Anthony Swarzak offered a glimpse of what will hopefully be a guiding veteran hand.