Power play dependent or power play dominant?
The Islanders had maybe the best power play of all time, and it was a big factor in their playoff success. Bossy was regularly called out by opponents and media as the most dangerous weapon on their power play and the player opponents tried to shut down. He was one of the most valuable PP players ever.
I guess it depends on whether or not you want to cast it as a positive or negative aspect of Bossy's scoring.
For his career, he had 739 ESP in 752 games (385 EVG/354 EVA), and 378 PPP (180 PPG/198 PPA), per game averages of 0.98 EVP and 0.50 PPP.
In the playoffs, in 129 games he had 84 ESP and 76 PPP, per game averages to 0.65 EVP and 0.59 PPP.
Absent Round 1, in 89 games he had 52 ESP and 62 PPP, per game averages of 0.58 EVP and 0.70 PPP.
If you just look at the four dynasty years, the Islanders averaged 4.134 goals per game in the regular season, and 4.666 in the playoffs. Here's a table broken down by strength:
| Games | Goals For | EV | PP | SH | GF/G | EV/G | PP/G | SH/G |
Regular | 320 | 1323 | 968 | 303 | 52 | 4.134 | 3.025 | 0.947 | 0.163 |
Reg Per 80 | 80 | 331 | 242 | 76 | 13 | | | | |
Playoff | 78 | 364 | 242 | 99 | 23 | 4.667 | 3.103 | 1.269 | 0.295 |
PO Per 80 | 80 | 373 | 248 | 102 | 23 | | | | |
In those years, Bossy had 312 ESP and 162 PPP in 313 games (0.996 and 0.517 per game, respectively, very close to his career averages), and 53 ESP and 58 PPP in 72 games in the playoffs (0.736 and 0.805 per game). He averaged about the same PPG, his mix was just different. As you can see from the per-80 numbers, the extra goals for the Islanders come from special teams, not so much even strength (depending on rounding its either 102 PPG and 23 SHG, or 101 PPG and 24 SHG, for 25-26 extra PPG and 10-11 extra SHG, compared to 6 extra EVG).
To give a series example, in the 79-80 finals against Philadelphia, the Islanders were outscored 10-19 at even strength in the series, but scored 15 power play goals in 6 games (they also had a shorthanded goal, to Philadelphia's 6 power play goals). Bossy had 1 even strength assist and 10 power play points (4 PPG/6 PPA) to lead the Islanders in scoring with 11 points. Is that a disappointing series because Bossy only had 1 even strength point in 6 games, or a good one because his 10 power play points contributed to the Islanders winning in 6 games?
Another example is the entire 80-81 run. In the first round against an awful Toronto team (-45 goal differential), the Islanders outscored them 20-4 in 3 games, Bossy had 10 points, 6 even stength, 4 power play. In the second round against Edmonton (+1 goal differential), the Islanders outscored Edmonton 29-20, including 14-11 at even strength, and also scored 13 power play goals in 6 games, with 2 shorthanded goals. Bossy had 2 even strength goals, 2 power play goals, and 7 power play assists. In the third round against the Rangers (-5 goal differential), the Islanders outscored them 22-8 in the sweep, Bossy had 1 even strength goal, 4 power play goals, and 1 power play assist. In the finals against Minnesota (+28), the Islanders outscored them 26-16, including 19-10 at even strength. Bossy had 3 even strength goals, 3 even strength assists, 1 power play goal and 1 power play assist. Was Bossy an even strength powerhouse due to scoring 12 ESP in 8 games against Toronto and Minnesota, or a disappointment because he had 3 ESP in 10 games against Edmonton and New York?