The first pitch of any at-bat is crucial. The pitcher wants to get ahead with strike one. The hitter wants to get something to hit. In many cases, it can set the tone for the whole plate appearance.
For the Phillies, it may also end that plate appearance. Entering play on Monday, the Phillies hitters have swung at and put the first pitch of a PA in play 50 times on the season, tied for the third most with the Miami Marlins. They’ve swung at the first pitch in general a total of 109 times, tied for 15th most with the Chicago White Sox.