WASHINGTON -- The Cubs' slumbering offense woke up a bit Thursday, staging a three-run comeback before succumbing to a 4-3 walk-off loss to the Nationals in the nation’s capital, where Alex Call’s game-winning homer off Brad Boxberger concluded Chicago's disappointing road trip on another frustrating note. But not before the news broke that reinforcements were on the way.

On Friday, the team promoted top first-base prospect Matt Mervis after the news first broke during the middle innings of Thursday’s series finale.

The 25-year-old Mervis emerged as one of the game’s best power prospects in 2022, when he cranked 36 home runs across three levels and led the Minors in extra-base hits, total bases and RBIs. He was also off to a strong start this year with Triple-A Iowa, hitting .286/.402/.560 with six homers and 27 RBIs in 24 games. Not only was Mervis continuing to crush Minor League pitching, but he was showing excellent patience in Iowa as well, walking (18) nearly as often as he struck out (19).

Here’s what the Cubs can expect from their No. 6 prospect, per MLB Pipeline: 

“Mervis features the best combination of power and contact in the Cubs system, and he took off when he improved his bat path and his swing decisions. His bat speed and the strength in his 6-foot-4, 225-pound frame are obvious, but he's more than just a masher. His relatively compact left-handed swing enables him to make consistent hard contact and he did a much better job of handling same-side pitchers in 2022 than he did in his debut.”

The Cubs made a corresponding move to add Mervis on Friday, optioning Edwin Ríos to Triple-A Iowa. The active roster also already features two established primary first basemen in Trey Mancini and Eric Hosmer, both of whom, like Mervis, offer little defensive flexibility. But he also joins a lineup that could use a shot in the arm after struggling mightily during its 1-6 road trip.

All told, the Cubs have averaged 3.5 runs per game and hit .180 with runners in scoring position over their past 12 games. They’ve lost 9 of those 12.

“These are definitely the moments that test teams,” said right-hander Jameson Taillon, who returned from the injured list to throw three innings in his first start since April 15. “But I think it helps that we’ve had a lot of guys who have run the race of 162 for many, many years. You know that these types of tough losses happen and you don't want to overreact. Obviously, it's not time to hit the panic button or anything. But I think we’re going home with maybe a sense of urgency, like, ‘Let's step on it a little bit, get back on track.'”

When the Cubs left Chicago a week ago, they were four games over .500 and fresh off a series win against the contending Padres, looking ahead to a pair of series against two of the NL’s weaker clubs. They will return a game below .500, having dropped three of four to the Nationals despite getting excellent pitching all week. That came Thursday in the form of Javier Assad, who cruised through five scoreless innings behind Taillon before the offense rustled to life.

Patrick Corbin held the Cubs to two hits over the first seven innings before Mancini (double) and Miguel Amaya (sac fly, MLB debut) tallied RBIs in the eighth. Nico Hoerner connected for a game-tying single off Hunter Harvey later in the frame, but Chicago squandered a second-and-third, no-out opportunity in the ninth before Call’s first-pitch homer off Boxberger.

The Cubs' offense splits so far this season are drastic:

First 19 games: 6.0 runs per game, .290 AVG, .820 OPS, .326 AVG w/RISP

Last 12 games: 3.5 runs per game, .235 AVG, .703 OPS, .180 AVG w/RISP

Maybe another bat will help. Enter Mervis, for what will be a much-anticipated MLB debut this week.  

“[Today] was a tough loss, for sure,” manager David Ross said. “Definitely a tough loss. But this group's shown they don't quit. They fight really hard.”