With the preface that I pay a little less attention to the individual performances of the European players, I'll do my best.
Filler
In a word, magnficent. Kept the runouts going when called upon to execute some tough shots. Played position well and broke respectably. Tactical skills are a bit underdeveloped, but why wouldn't that be the case for such a young player? Josh has a chance to be the best player in the world one day.
Shaw
Not the dominant Shaw we've seen in 2017, but still was a solid contributor. Not at his best in either of the singles matxhes against SVB, but managed to gain a split. I think Jayson is still trying to find his best form at the Mosconi, but I don't think we'll have to wait long. He and Filler will likely be the anchors of Team Europe in the foreseeable future.
Vandenberg
Nick doesn't seem to find his best at the Mosconi and, while his play was passable, I'd say he was Europe's weakest player.
Souquet
I think we saw, for the most part, the Ralf of old. Ralf was the best breaker of the balls on either team, played his usual superb patterns, and was adequate as a tactician. His pocketing was, perhaps, a little below the Ralf of the 2013 Mosconi Cup, but the standard was still high.
Alcaide
David's play was generally superb, and he showed a truly complete set of skills. His defense, kicking, and jumping were superb, and his jump carom of a nine ball off the three that followed a two way shot by Van Boening provided one of the highlights of Day 1 for Team Europe. David hadn't found his best in Mosconi Cups past, be he shone brightly in this one.
Teamwork
The Europeans always seem to play with more joy than the Americans, and this year was no exception. They really embrace the event to the max and have great team chemistry. Coach Chamat gets some of the credit, for he's an ardent cheerleader on the sidelines who amps up the energy of both his team and the European fans.
Well played, Europe.