The Nationals designated Williams for assignment Tuesday.
The roster move frees up a spot for waiver claim Matt Waldron. Williams has pitched well this season in long relief after returning from internal brace surgery, collecting a 2.65 ERA and 22:6 K:BB over 17 innings. The 34-year-old's $7 million salary will likely prevent him from being claimed off waivers, but he should receive some interest on the open market from a team in need of innings.