Chef shuffles at beloved neighborhood joints tend to be a gamble for loyal patrons — often as not new blood at the kitchen’s helm results in unwelcome changes on the menu. If you’re Jeremy Sewall — the culinary mastermind behind Eastern Standard, Island Creek Oyster Bar, the imminent Row 34, and Coolidge Corner’s Lineage — you have a knack for matching chefs with kitchens. Proof of this is Alex Sáenz, Sewall’s latest pick for chef de cuisine at Lineage.