Cover a rimmed baking sheet with foil, set a wire rack inside it, and coat the rack with olive oil spray. The rack should hold the roast above the pan so drippings collect below rather than soaking the bottom of the meat.
Stir the kosher salt, black pepper, garlic powder, paprika, sage, and thyme together in a small bowl. Mix until the herbs and spices look evenly distributed with no concentrated patches of salt.
Dry the pork thoroughly with paper towels, place it fat side up on the prepared rack, and press the seasoning mixture over every side before spraying the top with olive oil. The rub should form an even coating, with the fat cap still visible beneath the seasoning.
Heat the oven to 425°F and leave the seasoned roast at room temperature while the oven heats, about 30 minutes. This brief pause takes the chill off the exterior and helps the roast begin cooking more evenly.
Place an oven-safe meat thermometer probe in the center of the roast, roast for 15 minutes at 425°F, then reduce the oven to 375°F and continue until the thermometer reaches 145°F. Expect the herb coating to deepen in color and smell toasty during the first stage; this roast took about 75 minutes total, or about 25 minutes per pound.
Remove the roast, tent it loosely with foil, and rest it for 15 to 20 minutes before removing any butcher twine and slicing. The roast should feel firm but gently spring back when pressed, and resting keeps more juices in each slice.