Washington Nationals left-handed pitcher Sean Doolittle has progressed to throwing off of flat ground during rehab for his fatigued right knee. The southpaw tossed 20 pitches Tuesday, and is on track to throw again Wednesday should he not report any lingering injury concerns. Doolittle opened the year as the Nationals closer, but quickly ceded the job to Daniel Hudson after scuffling mightily out of the gate. Having averaged 26 saves over the past three years, its within the realm of ...