Complex sentence: Harris made his big-league pitching debut at Miller Park in Milwaukee against the Brewers on Saturday, April 25, in relief of starter Adam Wainwright, who had injured himself as he ran to first base on a pop out while batting.
Split into simpler sentences: Harris made his big-league pitching debut at Miller Park in Milwaukee against the Brewers on Saturday, April 25, in relief of starter Adam Wainwright. Wainwright had injured himself as he ran to first base on a pop out while batting.