Let me now praise Drew Barr. But let me first chide myself. Barr, the associate director of LCT's "War Horse," has been an absolutely essential part of the enterprise since the late spring of 2010, and I have only now got round to celebrating his contributions. 

So what exactly is his role here? In a conversation backstage the other day, Barr himself hesitated before defining it. "Nobody who works on 'War Horse' fully understands the dimensions of what they do until they actually do it." He describes his job like he describes the production itself: "always evolving." Generally speaking, he helps oversee the LCT production, working to ensure its high level of quality. He and Matt Acheson, the show's puppetry associate, effectively rehearsed the new cast members who came into the production last month. And Barr will act as director for the Australian tour of "War Horse," which begins rehearsals in October prior to its debut in Melbourne. 

Sounded out in February, 2010, about his interest in the show by Andre Bishop, LCT's artistic director, Barr went over to London in May of that year to meet with "War Horse"'s directors, Marianne Elliott and Tom Morris, and shortly thereafter signed up for his ever-morphing tour of duty. "It was a kind of homecoming for me," said Barr. "My first job ever in New York was as the stage-door receptionist at LCT, more than two decades ago. At the time, I was working on my master's in acting at NYU." He added: I feel incredibly lucky to be working here again." 

Barr, who has directed extensively in regional theater ("I tend to be known for re-inventing classic plays"), went on to assist Nicholas Hytner, the current artistic director of the Royal National Theatre in London, which developed and premiered "War Horse," on the LCT production of "Twelfth Night," in 1998. 

Throughout our conversation, Barr lavished compliments on the cast and crew of "War Horse." "I'm continually bowled over at how committed and tireless the cast and crew are," he said. Barr, though he is too modest to say it, is pretty hard-working himself. He watches the whole show at least three times a week, always searching for ways to keep the evening in artistic harmony. He has become one of the experts in implementing the ways in which, as he puts it, "each iteration of 'War Horse' learns and builds off the previous one." 

He also worked hard with "War Horse" co-director Tom Morris to create The Grid. It sounds like an action-movie villain but is, in fact, said Barr, "a spreadsheet that breaks down every scene of the play into 35 tracks for each actor." The longer that "War Horse" runs, the more useful The Grid becomes for each succeeding group of new actors. 

But "War Horse" will never harden into the mere lines and arrows of a software program. "Into our second year at LCT," said Barr, "we're still dealing with the basic questions of the play's story, and how best to convey it onstage. In the theater we like to say that no show is the same tonight as it was last night." He added: "With 'War Horse' that's doubly true. The constant rotation of roles, especially among the puppeteers, ensures that the evolution always remains intense." 

Brendan Lemon is the American theater critic for the Financial Times and the editor of lemonwade.com.