Orlando Bravo, the co-founder of the much-admired buyout firm Thoma Bravo, found himself in an unusual position last month—acting as a spinmeister and indirectly explaining away a miss. From its base in Chicago, Thoma Bravo manages roughly $180 billion, making it one of the largest nearly pure-play private-equity firms—and among the most aggressive investors in software. Its track record includes wins like its $2.4 billion acquisition of Dynatrace in 2014, which ultimately generated around $8 billion in profit. Bravo, himself, is worth about $12 billion. And yet there he was on CNBC, trying to calm the waters over a software company his firm owns, Medallia.