All dance companies are, inevitably, in perpetual transition, but that’s unusually pronounced just now at Pennsylvania Ballet, which opened a program of 21st-century choreography on Tuesday night at the Joyce Theater. Since Angel Corella became the company’s artistic director in 2014, large numbers of dancers have come and gone. Some of those dancing in New York this week have arrived since Mr. Corella joined the company, while others are in their final season. As this program shows, Pennsylvania Ballet draws strength from its base in Philadelphia, which in recent years has become one of America’s liveliest ballet cities. Its two resident troupes — this one (founded in 1963) and BalletX (founded in 2005) — usually perform in theaters across from each other on South Broad Street. They are also good examples of choreographic cross-fertilization, each commissioning premieres from at least three choreographers of note: Matthew Neenan (co-founder of BalletX and the resident choreographer of Pennsylvania Ballet), Trey McIntyre and Nicolo Fonte. Those men, who have all created new works for BalletX this season, are the authors of the three ballets on the Joyce program. All three employ taped music: This works best for Mr. McIntyre’s “The Accidental” (2014), the program’s centerpiece, which is danced to appealing songs by Patrick Watson. Having seen “The Accidental” when it was new in Philadelphia, I love again the wonderful self-contradictions of human behavior that Mr. McIntyre strings together into single dance phrases. A male-female duet begins with the man (James Ihde) standing. A final male solo abounds in singular incidents: In one fast step, Craig Wasserman arches sideways like a bow while extending one leg like its arrow. He ends both solo and ballet with a slow, marvelous and extraordinary gesture: Standing upright, he first holds his hands together high above his head, but then very slowly peels one hand down — down in a vertical line, down the other arm, down across his chest, down past his hip. As that hand and arm descend, they pull his upper body off-center, so that he seems to be hanging like a puppet from that one, still-raised hand; he seems also to have opened his heart to us. Mr. Wasserman, boyishly innocent and energetic, becomes more multifaceted as we watch. And Mr. McIntyre confirms his status as one of America’s most peculiarly original dance poets. This performance showed the marvelous musicality of his phrasing. Details of footwork (notably with Evelyn Kocak in the first song) and sweeps of phrasing were married to the music with a felicity that made “The Accidental” the highlight of the evening. “Grace Action,” by Mr. Fonte (who is to be the resident choreographer at Oregon Ballet Theater, starting this fall), closes the program and was the company’s greatest hit with the audience. Anyone can see why. It has stunning lighting by Brad Fields, with 12 searchlight-like lamps creating different beams across the stage (we might be in a planetarium); the dancers are dressed by Martha Chamberlain in midnight blue; and the Philip Glass music is easy on the ear.