DCC got to where it is — one of Ireland’s greatest stock market success stories — by keeping its head down and focusing on the numbers.  It was always a bit mysterious, but it didn’t matter. DCC’s bottom line was exceptional, and for a long time, that was all investors needed to know.  Donal Murphy was a big part of that success. Before being appointed CEO in 2017, he managed two of its three divisions, including its high-performing energy division. He has completed dozens of deals and travelled the world integrating businesses.  Now, Murphy faces a new challenge. DCC is under pressure.…