The answer to the question, is of course, both. But in what degree?
5 vs 5
I used behindthenet.ca's .xls files, with data from the 200708 season through the 201011 season.
EDIT: See post 22 for updated numbers  I used saved shots instead of total shots for these numbers.
Using the binomial approximation to a normal distribution, I calculated the zscore for each NHL player's onice shooting percentage over this time period, where zscore = (Onice GF  OnIce SOGF*LgSH%)/(Standard deviation calculated using binomial approximation)
Here are the players with the highest and lowest zscores
Player  Zscore  5on5 onice SH% 
SIDNEYCROSBY  6.42  13.3% 
HENRIKSEDIN  5.75  12.5% 
DANIELSEDIN  5.22  12.3% 
MARIANGABORIK  5.17  12.9% 
BOBBYRYAN  5.15  12.7% 
EVGENIMALKIN  5.12  12.4% 
RYANGETZLAF  4.98  12.1% 
ILYAKOVALCHUK  4.93  12.2% 
COREYPERRY  4.59  11.8% 
DANYHEATLEY  4.54  11.8% 
JASONSPEZZA  4.52  12.0% 
ALEXTANGUAY  4.36  12.1% 
NATHANHORTON  4.29  11.8% 
ALEXBURROWS  4.27  11.8% 
JAROMEIGINLA  4.27  11.5% 
RYANWHITNEY  4.21  12.1% 
PAULSTASTNY  4.14  11.8% 
MARTINST. LOUIS  4.12  11.5% 
MIKERIBEIRO  4.09  11.7% 
NICKLASBACKSTROM  4.07  11.4% 
ALEXANDERSEMIN  3.97  11.7% 
PAVELDATSYUK  3.86  11.3% 
DARRYLBOYCE  3.80  17.5% 
ALEXOVECHKIN  3.77  12.1% 
JEFFSCHULTZ  3.76  11.4% 
STEVENSTAMKOS  3.75  11.8% 
NICLASHAVELID  3.53  12.4% 
ALEXANDEROVECHKIN  3.48  11.7% 
BRENDENMORROW  3.48  11.6% 
JOETHORNTON  3.43  11.1% 
Player  Zscore  5on5 onice SH% 
TRAVISMOEN  4.09  6.0% 
SHAWNTHORNTON  3.91  5.8% 
COLTONORR  3.89  4.7% 
RADEKMARTINEK  3.79  6.3% 
ADAMHALL  3.78  5.3% 
BRENDANWITT  3.77  5.8% 
DEREKMEECH  3.69  4.7% 
CRAIGADAMS  3.66  5.7% 
RYANHOLLWEG  3.63  2.6% 
DONALDBRASHEAR  3.58  4.6% 
STEPHANEVEILLEUX  3.49  6.0% 
JEFFTAMBELLINI  3.45  5.9% 
ANDYGREENE  3.43  6.8% 
NATETHOMPSON  3.37  5.8% 
RODPELLEY  3.33  4.8% 
TODDMARCHANT  3.27  6.3% 
SAMUELPAHLSSON  3.23  6.5% 
RAITISIVANANS  3.19  4.5% 
FREDRIKSJOSTROM  3.19  6.3% 
TIMSTAPLETON  3.19  3.6% 
DANIELWINNIK  3.12  6.7% 
SCOTTGOMEZ  3.09  7.2% 
ANTTIPIHLSTROM  3.06  4.0% 
TOMWANDELL  3.06  5.5% 
ANDREWMURRAY  3.05  5.8% 
THOMASPOCK  2.90  4.3% 
JAMIEMCGINN  2.90  5.7% 
ANDREWPETERS  2.88  2.5% 
MIKEWEAVER  2.86  7.0% 
DALLASDRAKE  2.82  3.8% 
Generally speaking we see skilled players outperforming the league average and "less skilled" NHL players underperforming the league average in onice shooting percentage.
Taking the standard deviation of the zscores, I get 1.47. If random variation was the only factor, the standard deviation of the zscores would be 1.00.
Following the process from
this blog post:
Quote:
Step 1: Figure out how much one standard deviation is based on a binomial distribution. Vokoun faced 4249 shots, and the league average save percentage was .920, so one SD is sqrt (.92*.08/4249) = .0042.
Step 2: Figure out how much away you are from the mean. Vokoun’s save percentage was .931, and so was +.0108 from the mean.
Step 3: Figure out how many SD that is. .0108/.0042 = 2.59. That’s his zscore.
Step 4: Do it for all the goalies. (Thomas is 2.57, Luongo is 2.53… Holmqvist is 3.11, Raycroft is 2.34).
Step 5: Find the standard deviation of all the zscores. In this case, for these 55 goalies, it’s 1.38.
Step 6: Rejoice if the number is substantially higher than 1.00. Happiness sets in at 1.10. You did good at 1.20. If you get 1.40, you’ve definitely found something.
Step 7: Figure out the average number of opportunities for each player. In this case, the average shots faced was 2665.
Step 8: Do this: 1  1/1.38^2 = 0.47. That’s your r or rsquared. (Longer story later. Just call it r for now.) That 1.38 was from Step 6.
Step 9: Do this: (1r)/r * 2665. We get 2969. The 2665 is from Step 7.
That’s the key number. 2969. Let’s call it 3000. That’s how much you use to regress a goalie’s performance. You add 3000 shots of league average performance. So Vokoun’s 4249 shots at .931 save percentage gets added to 3000 shots at .920 save percentage for a bestestimate true talent level of .926. Holmqvist’s .900 with 1809 shots becomes .912. So, the observed difference between the two goalies (.031 saves per shot) becomes a true difference of .014.

Step 7: 768
Step 8: 0.54
Step 9: 657
So, given a player's onice shooting percentage from 200708 to 201011, the best predictor of his 201112 onice shooting percentage is his 200708 through 201011 shooting percentage plus 657 shots at a league average shooting percentage. Because Sidney Crosby was on the ice for 1867 shots at a 13.3 SH%, his predicted 201112% would be 12.2%.
Best and worst predicted 201112 5 vs 5 onice shooting percentages
Player  Predicted 5vs5 onice SH% 
SIDNEYCROSBY  12.2% 
HENRIKSEDIN  11.7% 
MARIANGABORIK  11.7% 
BOBBYRYAN  11.6% 
EVGENIMALKIN  11.5% 
DANIELSEDIN  11.5% 
ILYAKOVALCHUK  11.4% 
RYANGETZLAF  11.4% 
JASONSPEZZA  11.2% 
ALEXTANGUAY  11.2% 
Player  Predicted 5vs5 onice SH% 
COLTONORR  6.8% 
TRAVISMOEN  6.9% 
ADAMHALL  6.9% 
SHAWNTHORNTON  6.9% 
DEREKMEECH  7.0% 
BRENDANWITT  7.0% 
CRAIGADAMS  7.0% 
DONALDBRASHEAR  7.0% 
RADEKMARTINEK  7.1% 
STEPHANEVEILLEUX  7.1% 
I'll see if I can get the 201112 data to test the predictions.