Part of the appeal of Tom Colicchio’s dining empire over the few years of its existence has been its neat stratification, with Craftbar occupying a cozy, affordable middle ground between high-end Craft and lunchy-casual ‘Wichcraft. But in April, Craftbar moved around the block into a bigger, glossier space, and skewed away from the happy medium it had been.

The new restaurant seats 150 – more than twice the capacity of the old one – in a sleek, high-ceilinged room divided by a dramatic catwalk that accesses the wine collection. Red-paneled walls, brown-paper tablecloths, and whimsical paintings set a convivial mood, while offshoots and tributaries to the room offer more secluded dining. An overarching professionalism marks the service – which can slow down on busy nights but remains genial and glitch-free nonetheless. The smaller restaurant was casually catch-as-catch-can; this one accepts reservations and fills up fast.

Chef Akhtar Nawab’s seasonal, loosely Mediterranean menu has a lot to offer, but it, like the space, has edged toward the higher end. The old Craftbar offered a panoply of delicious and satisfying pressed sandwiches for around $10. Those sandwiches are gone now, and main courses start around $22. (‘Wichcraft, which serves sandwiches just around the corner, as well as at a new location in TriBeCa and at kiosks in Bryant Park, isn’t open for dinner.)

Mr. Nawab’s dishes typically marry a few interesting ingredients in smart, occasionally unexpected ways. And ingredients recur: In the spring, when ramps and fiddlehead ferns are in season, they find their way into half a dozen dishes. Some preparations only slightly tweak expectations, such as a small plate of mushroom risotto ($12) that’s tasty but ordinary, except for a distinctive creamy nuttiness that comes from an incorporated dose of mascarpone. Others play around with assumptions: A ramekin of fondue ($12) made with tangy, young pecorino cheese receives an unheralded but harmonious note of sweetness from acacia honey added to the melted cheese – a clever way to execute a classic pairing. A few whole hazelnuts founder in the fondue, too round and smooth to be rescued with the grilled rustic bread; they add visual interest, but culinarily they seem to have lost their way.

A bowl of three fried oysters ($10), familiar from the old Craftbar (but downsized from four), excels: The oysters are big, briny specimens with a cornmeal breading and fantastically flavorful, creamy bellies. Shreds of preserved lemon and a rich mayonnaise provide almost unnecessary counterpoint. More austerely, three pale-pink, lightly cured yellowtail pieces ($12) have a clean, almost astringent taste that’s accentuated by sprigs of fresh chamomile and sinuous, pungent pickled ramps.

Main courses offer a heavier and more protein-centric exploration of similar territory. In a deft, pleasing pork-on-pork preparation, Niman Ranch pork loin ($29) is roasted and cut into thick, abundantly moist slices, whose mild flavor is countered by hefty chunks of smoky bacon from which slow braising has removed much of the fat while intensifying the flavor. Sweet quartered beets and tender fiddlehead fern rounds add depth and freshness to the plate. Roasting also brings out the best in filleted loup de mer ($28), a Mediterranean sea bass: its skin is crisped and rich, and its flesh more juicy than flaky. Creamy white beans and cooked spinach give the dish heft.

A skate filet ($22), served with ramps and morel mushrooms and topped with a tomato preserve, has beautifully tender flesh with a crunchy sauteed exterior; but its fresh, delicate flavor was marred, at two separate meals, by an over-reduced, painfully salty pan sauce. Much better is a smallish bowl of exceptional house-made tagliatelle ($24), tossed with abundant pieces of sea urchin that give it a rich marine tang. The simple, buttery presentation exemplifies what the restaurant does best, showcasing excellent ingredients in wonderful harmony.

The Craftbar house cocktail ($10), which varies seasonally like the food, does the same trick – this spring it has been a lovely flute of subtle, lightly sparkling Clairette de Die wine complemented by little pieces of sweet rhubarb in the bottom of the glass, from which plumes of bubbles waft up dramatically. It, along with the restaurant’s peerless foot-long breadsticks, which are all savory crust and no chew, makes a graceful, appetizing start to a meal. The list of more than 300 bottles of wine runs a wide gamut, with a substantial French presence. Just a few bottles fall under $60, but plenty are above $200. By-the-glass choices are in the $10-$20 range and include some interesting choices, like an acidic, highly pairable Blaufrankisch ($11) from Long Island’s Channing Daughters, and the unusually complex biodynamic Sept Grains white from Alsace.

Anya Regelin’s desserts (all $8) don’t quite measure up: Though sweet and tasty, they have a certain ungainliness that doesn’t suit the orderly nature of the rest of the meal. A crumbly, oddly salty carrot cake comes with beautifully lined-up golden raisins reminiscent of the cooking of small children; a “crispy chocolate banana gateau” turns out to be a tiny cake smothered in melted chocolate, all wrapped in filo and accompanied by a scoop of clashing chai-flavored ice cream.

The restaurant is an excellent one, without question; the competent, assured, inventive cooking and stylishly comfortable space leave little room for complaint. But its conversion produces a sting of regret. What was once an unpretentious, no-reservations opportunity to sample the culinary precision of Craft has become another upscale dining establishment with few hints of what it was, leaving a hole in the middle ground.

Craftbar, 900 Broadway, 212-461-4300.