I was going to do research how Esposito performed in the games that Orr missed, but I double checked the archives and fortunately someone else had already done the work.
Link:
http://hfboards.mandatory.com/showthread.php?t=1297021
This post showed that during his time in Boston, Esposito scored 1.66 points per game with Orr in the lineup, and 1.32 points per game without him. That's the difference between a 129 and 103 point pace (over 78 games).
I think that probably overstates the difference because nearly half of the games that Orr missed were in 1968, when Esposito was a very good, but not dominant, scorer. (In fact, he scored more without Orr that season, but the composition of his points was markedly different - he scored more goals and fewer assists with Orr in the lineup).
That is the exact chart I was looking for too. A couple of things, I prefer to look at the season's individually. Because scoring was lower in 1968 than, say, 1972, so combining things into a big ball isn't the way to do it since there are different factors. For example:
1968 - 1.18 PPG without Orr (27 games), 1.10 with Orr
1969 - 1.55 PPG without Orr (9 games), 1.72 with Orr
1972 - 0 points in 2 games without Orr, 1.79 with Orr
1973 - 1.60 PPG without Orr (15 games), 1.68 with Orr
1974 - 1.25 PPG without Orr (4 games), 1.89 with Orr
1976 doesn't count because Orr was injured in all the games Esposito was still a Bruin. Other years Orr played in every game, or at least the ones Esposito played in. So we are left with a couple of telling things here.
For starters, he scored more without Orr in 1968 which is the one year that Orr missed the most time. We have the biggest sample size here and there is no indication that Esposito needs Orr. The next year is Esposito's Hart year and we have a smaller portion (9 games) to judge from and there isn't a whole lot of difference 0.17 PPG more with Orr. 1972 is a bit of a crapshoot. 2 games? Not enough really. I am sure there are other times Esposito AND Orr were pointless. 1973 is the next biggest indication of how things would go after 1968. It's 15 games. Esposito has 0.08 PPG less without Orr. That's a bigger sample size. 1974 is his other Hart year and I don't think 4 games tells us a whole lot. You can't tell me there aren't "droughts" with Orr where he has only 5 points in 4 games in his career.
So in conclusion, 1968 and 1973 are the most telling years and they show no evidence that Esposito wouldn't have still been THE superstar in the NHL without Orr.
How about his combined first four playoff appearances, three with the Hawks, one with the Bruins:
http://www.hockeydb.com/ihdb/stats/pdisplay.php?pid=1588
Total of 33GP 4G 7A 11PTS
Including a shutout in 1967.
Even the two posters boys for playoff futility amongst centers, post 1967 Joe Thornton -28GP 6G 12A 18PTS and Marcel Dionne 22GP 11G 11A 22PTS leave Phil Esposito in the dust.
Sure he bounced back starting with his fifth season but we have an explanation for the trade from Chicago to Boston. Parts of Esposito's career were far from great.
So how did the rest of the playoff careers go for Thornton and Dionne? Did they pick things up eventually? Did they lead the postseason in scoring three times after they were 24 years old? Did they win two Cups and have three Smythe worthy runs? Did their team fizzle away (1973) once they went down with an injury in the postseason?
See, I am glad people are so obsessed with how Esposito played in the postseason from the ages of 21 to 24 but why is that even a "thing"? Yes, it is included in his overall playoff career but does it really matter once we realized what the big guy actually ended up accomplishing? Basically Esposito's first 5 postseasons are similar to these legends' first ones:
Mark Messier (first three at least)
Pavel Datsyuk
Ted Lindsay
Bryan Trottier (first four at least)
Guy Lafleur (first three, no kidding huh?)
Milt Schmidt (first 4)
So what is the difference with these guys - along with Esposito - and Dionne and Thornton? Well, they actually are considered great postseason performers (Datsyuk probably the worst on there, but still). Yet it didn't start out that way. But does anyone really remember that Lafleur didn't take off in the NHL until 1975? Or that Trottier was part of an Isles team that was thought to be perennial chokers?
No, we look at the whole picture.