The teammates that matter are the ones that he's playing with. Hornqvist and Huberdeau are power play only teammates and PP is not driving Barkov's numbers nor where he makes his greatest impact (see below).
Barkov's line this season is the best 5 on 5 line in the NHL. Barkov trails only Valeri Nichushkin in xGF% at 5v5 this season. Verhaeghe is 5th (among Fs), Duclair is 9th, Matthews is 14th, Marchment is 36th. The Leafs 2nd line combo of Tavares-Nylander rank 46th and 27th. The best Panther forward that hasn't touched Barkov's line is 123rd and it's rookie Owen Tippett. Huberdeau ranks 264th - he is nowhere near as good as his point totals may make him seem and struggles to score/drive play away from Barkov.
Since we are trying to isolate the impact of Barkov and Matthews here, you absolutely have to consider linemates when comparing their stats. Matthews without a doubt has significantly better linemates so his numbers compared to Barkov's should be discounted. By how much? You can make that call but I would say the gap between Marner and anyone Barkov is playing with is massive. Marner is a star.
The last line is just a way of saying the Leafs haven't had a great PP. Barkov only has 2 more PP points than Matthews this year. Barkov is 16th in event strength points and 37th in PP points. As mentioned above and shown here, 5v5 is where Barkov shines.
The ice time difference is largely accounted for by PK time. In fact this season, Matthews is being deployed in much more favorable scoring situations. Matthews averages over 2 and a half minutes more 5v5 time per game than Barkov. This helps explain a portion of the gap in total points. Matthews still holds the edge in P/60 at 5v5 but only 3.07 (3rd) to 2.78 (11th).
As you say, the stats are very close with Matthews having a slight edge. This is where people voting Barkov here would say that you need to apply some adjustment for quality of teammate/opposition which surely favors Matthews in both cases. Considering Barkov is better defensively as well, we believe this pushes him over the edge.
I actually posted a couple of links on aging curves here on page 2 of the thread though obviosuly they've gotten lost so posting below again for reference.
https://hockeyviz.com/static/pdf/ritsac19.pdf
A New Look at Aging Curves for NHL Skaters (part 1)
In short, research has shown that peak forward age is actually around 23-24. Obviously this can vary player by player but important to note that Matthews is this age now. If Matthews follows historical trends (he very well may not), we could expect a slight decline in the next 3 years. I don't believe the age difference holds up because we can't guarantee continued improvement from a 23 year old. Also per the curves, production at 21-23 is not noticably worse than 24-26.
TLDR: Everyone here admits the overall offensive stats are close with Matthews slightly on top. Matthews is clearly the better goal scorer (best in the league). Barkov is the clear better playmaker and currently the driver of the best line in the NHL at 5v5. To isolate the impact of these indivuals, we should adjust for quality of teammates and competition. Considering Matthews has the clear advantage there, any difference in offensive numbers is marginal at best. Since Barkov holds the defensive edge, many people consider him the better player. I think an argument for Matthews would start by suggesting that the gap between teammates is not that wide but I can't personally see that.
Appreciate the lengthy data driven reply.
So, a few counter arguments:
It's true that Matthews is entering the period of time that is normally considered to be the most offensively productive of the average player's career.
However, since many players don't have lengthy careers and are out of the league within a few seasons, those stats are not as reflective or relevant to the very top players - see the longevity of top end performers like Ovechkin, Crosby, Malkin, etc. There might be some drop off, but their careers don't resemble peaks, more like gentle hills with low slopes on the tail end.
I believe that Matthews is one of the very best offensive players in the league, has not hit his peak in any way, and will be just as graceful in the later stages of his career as someone like Ovechkin.
Whereas Matthews is just starting to enter it, Barkov is now exiting that peak point, as you point out.
I also believe that Barkov will not have a sharp decline in offensive production, although I do think he's at the absolute peak of his offensive production.
See, the difference here, even if we consider these 2 players to have similarly slow drop offs in their careers, is that while Matthews is just starting to get to that sweet spot, Barkov has already been there for the last couple of years and is about to leave it.
For players with remarkably similar offensive production thus far, this gap will only widen significantly in the next 3 years or so.
Again, this is just following the logic provided by that study, which I don't put as much stock into for this caliber player to be honest.
I don't believe that the difference in defensive metrics makes up for what will undoubtedly be a significant offensive difference coming in the imminent future. We see more than signs of this gap widening already, and when one player's career is still on the upswing, and the other is at plateau or starting the slow decline from it, the gap will only continue to grow.
The honest truth is that since the start of last season, Barkov is sitting at 1.03 ppg, Matthews is at 1.22 ppg.
As for the teammate argument.
It's no surprise that Marner and Hyman/Thornton are better linemates.
Don't forget though, the already superior offensive production by Matthews includes 2 full seasons of rookies as his linemates nearly 100% of the time.
He entered the league with 9 total rookies on his team, a team dead last the previous season.
During the first 3 seasons in Toronto, Matthews' linemates were - Zach Hyman, William Nylander, Andreas Johnsson, Kasperi Kapanen, Connor Brown.
He made Kapanen into a 20 goal scorer, did the same for Johnsson.
Hyman and Brown are not exactly stars, although Hyman has steadily improved over the years.
Nylander has been great, good, ok, decent, bad, brutal over his career. He has been exactly what he was projected as, and also spent some time in the 3rd and 4th lines.
It was not until this past year that Matthews played with Marner full time. He has barely over a full season with Marner now, and he's scoring at a pace of 60 goals and over 100 points per year since.
It is true that as a whole, Matthews has had better linemates, but it's completely unfair to point at Marner and say "see, that's who has been helping Matthews this whole time, that's the real difference between his production and that of Barkov". Truth is that since Matthews and Marner started playing together 5 on 5 (the first game after Keefe took over from Babcock), he's been one of the 3 best offensive players in the league, and has blown everyone out of the water in terms of goalscoring (by some margin).
I guess, the question really is, what is better:
The established elite defensive player who is also very good offensively, but at an age where offense generally starts to slow down.
or
The established elite offensive player who is also very good defensively, at an age where his offensive numbers will continue to climb for a few years, but whose defense will also continue to improve.
And to me, that is plain.
