It is a sobering thought on the randomness of such an event that Starlin Castro, the most recent to do this before Soler and who did it in the same location, Great American Ball Park in Cincinnati, has hit more than five times as many career home runs as four of the other five combined. That ought to tell you a lot about the temporary fame of most of the other Cubs who did this. Further, including Soler's blast, the Cubs are just 4-3 in games in which one of their players has gone deep in his first time to the plate in the big leagues.
Here are the details of all six previous Cubs who homered the first time they stepped to the plate in the major leagues.
September 11, 1942, first game, Paul Gillespie: Gillespie's solo shot off Giants righthander Harry Feldman gave the Cubs a 1-0 lead. Gillespie later drove in another run with a single, but the Cubs lost 4-3 when Hiram Bithorn issued a bases-loaded walk in the bottom of the ninth. Gillespie, a catcher, would hit just five more homers, one of which was in his final regular-season at-bat in the first game of a doubleheader September 29, 1945. Gillespie is one of just two players to homer in both their first and last big-league at-bats. He went 0-for-6 in the 1945 World Series.
May 24, 1957, Frank Ernaga: Ernaga, whose last name is also the user name of a regular BCB poster who can probably fill in even more details on this, homered in his first at-bat off future Hall of Famer Warren Spahn in the second inning, tying the game 1-1. He later tripled in a run that gave the Cubs the lead they would never relinquish in this 5-1 win. Two days later Ernaga homered again, in the eighth inning of the second game of a Wrigley doubleheader against the Braves, off future Cub Juan Pizarro. The blast tied the game and the Cubs won in the bottom of the ninth. Sadly, these would be the only two homers of Ernaga's career.
September 1, 1961, Cuno Barragan: Just after Andre Rodgers had hit a two-run homer off Dick LeMay of the Giants, Barragan followed back-to-back with a homer to left in his first big-league at-bat, giving the Cubs a 3-0 lead... which they blew and lost the game in 14 innings, 4-3. Barragan, a catcher, was a 29-year-old rookie at the time of his blast, and played in just 68 more major-league games, never homering again.
August 22, 1983, Carmelo Martinez: The only one of these players to have any significant major-league career (until Castro), Martinez was a hyped rookie, having hit 31 home runs that year at Triple-A Iowa before his callup. His homer in the fourth inning off the Reds' Frank Pastore helped the Cubs to a 2-0 win, and he hit six homers overall in 89 at-bats that year. After the season he was traded to the Padres in a three-way deal with the Expos that brought Scott Sanderson to the Cubs. He wound up with 108 lifetime homers -- the only one of this group before Castro who hit more than six total -- in a nine-year career that included stops with the Phillies, Pirates, Royals and Reds.
June 8, 1992, first game, Jim Bullinger: Bullinger, a converted shortstop, had pitched in three games before he came to the plate. He had entered the game to relieve starter Shawn Boskie after four innings, and came to the plate to lead off the fifth, and hit Rheal Cormier's first pitch over the left-field wall to give the Cubs a 1-0 lead; they eventually won the game 5-2 in 14 innings. Of the 117 players (including Soler, who is the first player to do it in almost two years, since Jurickson Profar September 2, 2012) to homer in their first MLB at-bat, Bullinger is one of just 27 to hit that blast on the first big-league pitch he saw, and one of just six pitchers to do so.
May 7, 2010, Starlin Castro: After his three-run homer in the second inning off the Reds' Homer Bailey, Castro smacked a bases-clearing triple in the fifth, becoming the second Cub to homer and triple in his big-league debut. The six RBI are a major-league record for anyone's first major-league game, and if he has the career we hope he's on track for, he could wind up with more career homers than any other Cub who accomplished this feat in his first big-league at-bat.