I don't think Bo has established himself as a top pair D yet. Wildly inconsistent and has had repeated defensive lapses throughout the season. In Game 5 against Seattle when Makar was out and you'd want him to step up, he had the worst metrics on the team 32% xGF in 24 minutes of 5v5 ice time. Toews far outplayed Bo in the Seattle series.
And this is before you consider the injury history and the risk there.
Bo has the potential to be a top pair guy, but he's not there yet and I think his game was in better shape during the Cup run than the previous season. Didn't take a step forward (injuries didn't help of course), probably went a little backwards.
I have lots of thoughts on this, so apologies for the long post.
When Bo first played on the top pair this year with Makar, I think he made it pretty obvious he not only was capable of playing in that role, he excelled at it. There was a noticeable improvement on the team IMO when they first swapped Toews with Bo. He made Makar better as well.
I think Bo made some uncharacteristic mistakes at times this year, but his defensive lapses were overstated compared to others on the team. It was a reaction to him being highly praised beforehand. There's a natural tendency for some to tear down the king or the heir apparent, by holding them to a higher standard than others.
In reality the entire D core struggled a lot this year. They all tried to do too much with a depleted roster.
On a per game basis, I would bet Toews and even Makar had more mistakes than Bo. Cale had lots of them this year. More than any other season. Toews was quite bad in a lot of games this year. Manson struggled in the games he played trying to play through a high ankle sprain. MacDermid struggled more than last season.
JJ and EJ were about the same IMO, but EJ was forced into a bigger role with the injuries on the right side to Manson and Makar. Also when both were in the lineup, he was forced to play on his off left side for really the first time in his career, which has never been a strong suit of his, because Bednar/Pratt wanted to run a true top 4 and play Girard/Toews on their off right side, and they moved EJ to the left instead of Manson. I think this is why JJ was slotted to play ahead of EJ to start the playoffs.
Sammy who often times has struggled with mistakes in the past I think was quite good in the second half of the season. I think he has a lot of pride, and increased his intensity in his D zone battles to overcome his limitations. He wasn't perfect, but it was great to see him improve.
Bo for the bulk of his season was quite good, but was kind of up and down to end the regular season and a few times in the playoffs. So I think there's some recency bias there in evaluations of him. But this is also when they were pushing the hardest to win the division and advance in the playoffs with a depleted roster that kept getting worse.
Toews I agree was better than Bo against Seattle, but I think this was because Devon had been struggling defensively most of the year, so he really simplified his game and didn't try to do much of anything offensively. IMO the right balance for the situation they were in with a depleted roster, was somewhere between how Bo and Devon approached the role.
Bo on a strictly talent and IQ/awareness basis, I still maintain is the best defenseman defensively on the team. His defensive reads are a clear notch above the other D men. He makes more subtle old school "smart" defensive plays than other D men on the team. He separates guys from the puck and boxes them out in the corners better than other D men on the team. His desperation plays in bad situations are often better than the others. He's got a good active stick. These are the true defensive plays that you should judge defenseman on that don't show up in stat sheets.
What Bo struggled with the most though at the end of the year was turnovers in the D zone. It also impacted some of his coverage, because I think the root of the problem was he was thinking too far ahead offensively with the team desperately needing offense. These are classic young defenseman problems though. Not an indicator of how truly good he is defensively.
He was trying to help the team offensively with so much offense missing, but I think he let his focus get ahead of the play, instead of focusing on reading the play in front of him first, and letting that guide him. Usually this is a strength of his though, so that's why I don't see it as a long term problem. Just a young defenseman's problem at the highest level of hockey with little margin for error.
He just needs to iron out the consistency, that's the main issue with him right now, but that's the same for every 21 year old D man like him. He's only played 91 regular season games, but for some reason people hold him to the same standard as 300+ and 400+ game defenseman like Devon Toews or Sam Girard. Compared to other 91 game NHL defenseman though, he's playing outstanding.
He's still learning what works and what doesn't for him at the NHL level. He'll figure it out pretty soon I think. He's a quick learner and he's just too good not to.