My apologies, Vanislander. I was a little short on time earlier, but wanted to throw my two cents in. I can expand a little bit more now, although most of the points I would make have already been covered by other posters. I typically don't care for "what ifs," but I'm procrastinating on doing some much needed housekeeping (shows you how much I really don't want to do it).
Both players have two Stanley Cup championships. Both have two Conn Smythe awards. Pretty even there. Lemieux has six Art Ross awards to Orr's two. However, since Orr is a defenseman, I think the fact he has even one Art Ross on his resume is more impressive since no other defenseman has had one. Has another defenseman even finished number two in scoring? If so, my money would be on Paul Coffey. I digress...
I guess I'm going to make my stand based on one series. That would be the infamous 1979 "Too Many Men on the Ice" series against the Canadiens. I was four years old at the time, so I don't remember it. I had other priorities and it was on past my bedtime.
Anyway, the Bruins battled the mighty dynastic Canadiens to an absolute standstill and it took a colossal Bruins blunder and the greatest goal ever scored by Guy Lafleur for Montreal to win the series. As it stands, it is in my opinion the greatest series in NHL history. I despise the result, but for drama, I can't think of a better series ever.
So what happens if a healthy Bobby Orr (still playing for Boston) plays in that series in an alternate timeline?
I have to believe that a healthy Orr would have been the difference in Game 7.
Lets assume that Coach Cherry still replaces Cheevers with Gilbert after Game Two.
In our universe, Games One; Two; and Five were decided by two; three; and four goals respectively. In the alternate universe, I'll assume that Montreal still wins those games - but with the addition of Bobby Orr, the scores are much closer.
I'll also assume that the Bruins win Games Three, Four, and Six at home just as they did in our timeline. In our universe, Games Three and Four were decided by one goal. Game Six was decided by three goals. The Bruins were gaining momentum.
Which brings us to Game Seven. History as we know it has the Bruins losing 5-4 in overtime.
But with Orr and Park on defense together, once the Bruins built their lead, they would more likely than not add to it, or at least maintain it. But how would Orr do offensively? There really IS no way of knowing. What I did was take Orr's career playoff stats and average them out like he was in a bowling league. In 74 career playoff games, Orr averaged .351 goals per game; .891 assists per game; and 1.243 points per game. So, over this seven game series, lets say he had a line of 3-6-9. I did a little rounding up to make some of the numbers work. I don't think that's a bad line for this series. It puts Orr behind Guy Lafleur's 12 points and ties Jean Ratelle's 9 points for the series. Very good for a defenseman, I think.
I believe that Orr sets up at least one more Boston goal in regulation and the Bruins survive the Montreal onslaught in the third period. The too many men on the ice penalty becomes a footnote as the Bruins hold on for a 5-4 win in regulation and easily dispose of the Rangers in the Finals.
So, what's my point? My point is that Orr earns a signature playoff triumph against a dragon he was never able to slay in our timeline. What is or would be Mario's? This wasn't trouncing the expansion St. Louis Blues in a four game sweep. This was a hockey donnybrook that resulted in a 15 round knockout. Yes, Orr still has his iconic 1970 Cup-clincher, but he never had a series like this one. Only the 2004 ALCS triumph of the Red Sox over the Yankees could compare to the '79 Semi-Final had it gone the Bruins' way. It paves the way for a THIRD Stanley Cup championship for Orr; possibly a third Conn Smythe (however, I think Gilles Gilbert gets it); and makes Orr a hero in a bitterly contested series for the ages. Orr's Bruins even take a nice big bite out of the Montreal dynasty to boot. Even had Mario Lemieux remained healthy, would he EVER have faced anyone as fearsome as the 1979 Canadiens? No. No way in hell.
This one game in this one series changes so much for Bobby Orr. Leaving 1979 aside for a moment - could there have been other Stanley Cup championships? Maybe. More scoring and bigger stats? Absolutely. The whole structure of the NHL changes with a healthy Orr skating for the Boston Bruins.
My two cents.