Yes if you "broaden the sample size" to make the vast majority of the sample Matthews down year when he was hurt, the numbers do look closer. But it seems like this year will be a lot closer to his 2nd and 1st place Hart seasons.
Yeah he's been awesome this year, but he's also been running pretty hot while Stutzle has been running cold.
Look at their 5v5 numbers:
Stutzle
1 goal vs 2.33 ixG (-1.33)
9 GF vs 7.58 xGF (+1.42)
8.91 on ice sh%
Matthews
7 goals vs 3.65 ixG (+3.35)
13 GF vs 8.38 xGF (+4.62)
13.83 on ice sh%
And in all situations
Stutzle
2 goal vs 3.97 ixG (-1.97)
16 GF vs 17.63 xGF (-1.63)
10.0 on ice sh%
Matthews
13 goals vs 7.4 ixG (+5.6)
25 GF vs 19.13 xGF (+5.87)
14.37 on ice sh%
I would expect Matthews to have a higher 5v5 on ice sh%, but their career averages suggest the gap should be ~1.5-2.0 percentage points, not 4. Matthews is outperforming his career avg oish% of 10.5% by 32%, while Stutzle's oish% is only 3% higher than his career average of 8.61%.
If they continue to play at the levels we've seen, I'd expect Matthews to outpace Stutzle by 10-15 goals and roughly the same amount of points.