BALTIMORE -- Last year, Hanser Alberto famously went from four-time waiver claim to American League batting-crown contender in the span of a few months. It was a turnaround not even the Orioles saw coming, especially not when they first selected him in January, nor when they jettisoned him a little more than a month later. Of course, Alberto eventually found his way back to Baltimore via another waiver claim from the Giants, made the team and turned into an out-of-nowhere 3.1 WAR player.

What surprises await the Orioles this summer? On a team with so much opportunity, it's entirely possible that another unknown entity emerges as a contributor over the course of the summer. Here are a few candidates -- seven players acquired this offseason who could impact the O's in 2020, even if their arrivals flew a bit under the radar.

1) Infielder Dilson Herrera
Acquired: Minor League free agent

Once a blue-chipper in the Mets' system, Herrera’s prospect shine has dimmed since he was traded to Cincinnati for Jay Bruce in August 2016. But Herrera is still just 25, and he experienced a power surge at Triple-A Syracuse last season, when he hit .248/.330/.501 with 24 homers. Herrera is just a career .203 hitter in 102 big league games, and he will have to earn a 40-man roster spot this spring. He’s expected to get reps at a handful of positions, including as a right-handed complement to Rio Ruiz at third base.

2) Right-hander Isaac Mattson
Acquired: Trade from Angels

Keep an eye on Mattson, the most big league ready prospect acquired in the four-player package for Dylan Bundy in December. A 24-year-old former 19th-round pick, Mattson rose quickly through the Angels’ system on the heels of gaudy strikeout numbers, using swing-and-miss stuff that translated at every level. He stockpiled 110 whiffs in 73 1/3 innings in 2019, including 19 in a 9 1/2-inning sample at Triple-A Salt Lake. He will probably begin the year at Triple-A Norfolk with a chance to be in Baltimore before long.

3) Left-hander Rob Zastryzny
Acquired: Minor League free agent

An Orioles import with Cubs ties? You don’t say. Add to the list Zastryzny, who earned a World Series ring with Brandon Hyde in Chicago in 2016. Zastryzny contributed 16 innings of mostly long relief as a rookie that season, posting an impressive 1.13 ERA.

But it’s been a struggle for the former second-round pick since, both at Triple-A Iowa and Triple-A Oklahoma City (5.61 ERA in 197 1/3 innings from 2017-19) and the Majors (7.23 ERA in 18 2/3 innings from '17-18). The Orioles were hurt badly by their lack of starter depth last summer. Now Zastrynzny gets an opportunity to provide that.

4) Right-hander Cole Sulser
Acquired: Waiver claim from Rays

Sulser is a late bloomer who spent parts of the past four seasons at Triple-A Columbus and Triple-A Durham, and he didn’t debut until last season, at age 29. But he did well enough in a short sample (nine strikeouts over 7 1/3 scoreless innings) for the Orioles to pluck him off waivers in October, looking to add option to their always-shuffling mix of bullpen arms. Sulser struck out 193 batters in just 134 innings since the start of 2018, between Double-A, Triple-A and the Majors.

5) Utility man Richard Ureña
Acquired: Waiver claim from Blue Jays

A switch-hitting utility type, Urena hit .253/.300/.336 with little power over parts of the past three seasons with Toronto. But he doesn’t turn 24 until next month and is a natural shortstop, a position at which the Orioles are lacking, organizationally. Expanded rosters give him a chance to break camp with the club, especially if it decides Richie Martin is better suited to open the year at Triple-A.

6) Right-hander Cesar Valdez
Acquired: Minor League free agent

The soon-to-be-35-year-old Valdez has had an unusual career. He debuted with the D-backs in 2010, but then he went seven years before returning to the Majors, appearing in 11 games for the A’s and Blue Jays in '17. He has spent the two seasons since in the Mexican League and the Dominican Winter League, where he has thrived. Last year in 30 appearances (29 starts) across both circuits, Valdez went 19-3 with a 2.01 ERA and a 7.71 strikeouts-to-walks ratio.

7) Catcher Bryan Holaday
Acquired: Minor League free agent

An eight-year veteran, Holaday has experience as a serviceable backup for the Tigers, Rangers, Red Sox and Marlins. His past two seasons were spent in Miami, where he hit .237 with five homers in 104 games. He is probably ticketed to split time with Austin Wynns at Norfolk, but an injury to Pedro Severino or Chance Sisco could create the opportunity for big league at-bats.