The Chicago Cubs today placed outfielder Jason Heyward on the seven-day concussion disabled list (retroactive to May 7) and recalled infielder David Bote, right-handed pitcher Jen-Ho Tseng and left-handed pitcher Rob Zastryzny from Triple-A Iowa. Right-handed pitcher Cory Mazzoni has been optioned to Triple-A.
Tseng (who will be Chicago's starting pitcher), Bote and Zastryzny will all be available for the Cubs tonight as they continue their three-game series against the Miami Marlins at Wrigley Field.  
Bote, 25, returns for his second stint with the Cubs this season. He made his big league debut with the club last month, hitting .111 (1-for-9) with a double in three games with Chicago. With Iowa this year, Bote is batting .333 (27-for-81) with five doubles, one triple and five home runs in 20 games, posting a .998 OPS. He is batting .517 (15-for-29) in seven games in May, including his first-career five-hit game last Sunday at Round Rock.
The right-handed batter and thrower enjoyed a breakout season last year with Double-A Tennessee, batting .272 (128-for-470) with 30 doubles, three triples, 14 homers and 59 RBI in 127 games while turning in a .792 OPS to earn mid- and post-season Southern League All-Star honors. Bote continued his strong 2017 by hitting .333 (23-for-69) with four homers, 14 RBI and a .931 OPS in 19 games in the Arizona Fall League to earn All-Star honors.
Tseng, 23, made his major league debut with the Cubs last season, going 1-0 with a 7.50 ERA (5 ER/6.0 IP) in two appearances, one as a starter. He has pitched exclusively with Triple-A Iowa this year, posting an 0-4 record with an 8.04 ERA (28 ER/31.1 IP), fanning 32 batters in 31.1 innings pitched. 
In 2017, Tseng was named Chicago's Minor League Pitcher of the Year after going 13-4 with a 2.54 ERA (41 ER/145.1 IP) this season in 24 starts between Double-A Tennessee and Iowa. In 15 starts with Tennessee, Tseng went 7-3 with a 2.99 ERA (30 ER/90.1 IP), fanning 83 batters and walking 24. He was promoted to Triple-A for the first time following his first-career 10-strikeout game, July 3 vs. Jacksonville. The right-hander excelled in Iowa, posting a 6-1 record to go along with a 1.80 ERA (11 ER/55.0 IP) in nine starts.
Tseng was signed as a non-drafted free agent by Chicago in July of 2013. He holds a career 32-24 record and a 3.47 ERA (198 ER/514.0 IP) in 93 games (91 starts) across five seasons in the Cubs system. Tseng was also named Chicago's Minor League Pitcher of the Year in 2014.
Zastryzny, 26, joins the Cubs for the first time this year after spending parts of the last two seasons in the big leagues with the club, combining to go 1-0 with a 4.34 ERA (14 ER/29.0 IP) in 12 major league relief appearances, all but one in relief. With Iowa this year, Zastryzny has gone 2-0 with a 2.35 ERA (4 ER/15.1 IP) in eight relief outings.
The southpaw was originally selected by the Cubs in the second round of the 2013 Draft out of the University of Missouri. He is 21-20 with one save and a 4.60 ERA (207 ER/405.1 IP) in 98 minor league appearances, including 78 starts, in six minor league campaigns.
Heyward, 28, is batting .227 (22-for-97) with three doubles, two homers and 14 RBI in 29 games with Chicago this year.
Mazzoni, 28, has gone 0-2 with a 2.31 ERA (3 ER/11.2 IP) in eight relief appearances for Iowa this season. He pitched a scoreless ninth inning last night to close out Chicago's 14-2 win against Miami.