In their 2016 mid-season update, Baseball America advanced Lopez 44 spots and ranked him as the No. 48 prospect in Minor League Baseball.
The promising 22-year-old joins the Nationals' Major League roster tied for ninth in Minor League Baseball with 109 strikeouts, as well as fifth in strikeouts-per-nine-innings (11.23), among Minor League pitchers with at least 80.0 innings pitched this season. From May 29-June 25, just before his promotion to Triple-A, Lopez posted a 2-1 record with a 1.60 ERA (6 ER/33.2 IP) in six starts. In that span, he struck out 56 batters - including four double-digit strikeout games - and walked just five. He did not allow a single ball to leave the yard.
A native of San Pedro de Macoris, Dominican Republic, Lopez represented the Nationals at MLB's 2016 Sirius/XM All-Star Futures Game in San Diego earlier this month. In his one inning of work for the World Team, Lopez was clocked as high as 99 mph with his fastball.
Since signing as an international free agent on June 21, 2012, Lopez's ascension through the organization has been steady. He spent the entire 2015 season at Single-A Potomac, where he set career marks in games started (19), innings pitched (99.0) and strikeouts (94). He earned the designation as the No. 4 prospect in the Carolina League (per Baseball America) at the conclusion of the season. That came on the heels of his breakout year in short-season Single-A Auburn and Single-A Hagerstown in 2014, where he finished as the No. 3 prospect in the South Atlantic League (Hagerstown) and the No. 2 prospect in the New York-Penn League (Auburn).
When he makes his MLB debut on Tuesday night vs. the Los Angeles Dodgers, Lopez will become the first Dominican pitcher signed and developed by the Nationals (2005-present) to start a Major League game. He joins right-hander Yunesky Maya as the only Latin American players originally signed by the Nationals to start a game for them.
Solis, 27, has posted a 2.43 ERA out of the Nationals' bullpen this season, along with a 1-3 record. The left-hander has struck out 10.3 batters-per-nine-innings in 25 appearances over 29.1 innings pitched.
de Los Santos, 23, appeared in two Major League games for Washington in 2015. He allowed one earned run on two hits in 1.2 innings of work. He is 1-1 with a 3.67 ERA this season for Double-A Harrisburg and Triple-A Syracuse, collecting five saves in 11 games finished (29 appearances, 34.1 IP overall).