Yes, albeit on a lesser scale than adding or losing a great player.
It might seem obvious, but yes they do. Some people might not think so because head coaches are constantly made the scapegoat for bad team records and fired so people just kind of dismiss their impact. Which I think is kind of a shame, because yes while head coaches definitely have an impact, they also cannot control which players get injured or for team chemistry and things like that, and are often blamed if they can’t make things work out.
Thing is when it comes to the regular season, the impact of coaches is somewhat less visible than in the playoffs, which is where you really see if there’s two really good teams in a 7 game series, the team with the better coach usually wins out.
I have some notable examples where you can see a head coach making a difference:
Red Auerbach of course is one of the greatest coaches, but I think in particular it was his executive acumen and his embracing of black players that really had a part in his success. Drafting Cousy, Russell, Heinsohn, both KC and Sam Jones, Havlicek, etc that’s an incredible eye for talent, and then of course revolutionizing team defense with Russell.
Alex Hannum made an immediate impact when he was head coach of the Hawks, Warriors and 76ers. He led the Hawks to 2 straight NBA Finals, winning one. He was also instrumental in getting Wilt to play ‘the right way’ and made him share the ball more, and under Hannum, Wilt made 2 Finals in 1964 and 1967 and won in 1967.
Bill Sharman led the Warriors to a Finals in 1967, and the Lakers to 3 Finals in 1970, 1972 and 1973, winning it in 1972. He was instrumental in creating the morning ‘shoot around’ to get players in the rhythm.
Usually when you see a head coach lead different rosters to different Finals, you know that they are a great coach since they are clearly able to make effective plays and create success for multiple rosters and teams.
Red Holzman was instrumental in the Knicks success in the 1970s especially emphasizing defensive team play as well.
Tom Heinsohn continued the Celtics winning streak which actually came down to 2 close 7 game series in the Finals in both 1974 and 1976.
Pat Riley obviously took over a great Lakers team inherited from Jack McKinney and Paul Westhead and led them to even greater heights in the 1980s leading them to a total of 6 Finals appearances in the 80s. The Knicks had their greatest success since the 70s with Riley as coach. With the Heat he was also a factor in their first championship as well.
Phil Jackson of course took over an already very good NBA coach in Doug Collins, but was the extra factor needed to push Jordan’s Bulls to the championship level. Additional proof of Phil’s greatness, is he took over a talented Lakers team in 2000 (who previously could not get past the 2nd round under Del Harris) and immediately took them to a 3-peat and 4 total NBA Finals. And of course, Phil was instrumental in another 3 consecutive NBA Finals guiding the Kobe/Gasol Lakers to 2 championships.
Larry Brown took 3 different teams to the Finals; the ABA Nuggets, the Iverson 76ers and the 2000s Pistons to back to back Finals, winning one in 2004. He’s a coach that jumps around a lot, but his impact can be felt with every team he’s coa
Gregg Popovich of course his success is so tied to Tim Duncan, but what’s impressive is how Duncan and him won championships with essentially three different incarnations of the Spurs – the 90s Spurs where Duncan co-starred alongside Robinson, the 00s Spurs where Parker and Manu co-starred, and the 10s Spurs where we see Duncan, Parker and Manu aging but Kawhi emerging as their next star. He led all of them to a championship.
Steve Kerr took a Warriors team that had only gotten to the 2nd round under Mark Jackson, and turned them into a championship team his first season of coaching. Immediate impact. Led them to 5 consecutive NBA Finals, truly an impressive feat.
And for a more recent impactful story, just take a look at the Boston Celtics.
2021 Boston Celtics – coached by Brad Stevens, very talented roster. Lost in the first round against the KD/Kyrie Nets.
2022 Boston Celtics – coached by Ime Udoka, same roster, played like a totally different team. Not only did they sweep that same KD/Kyrie nets team in the first round but they went all the way to the Finals, and they were much better defensively.
See how much coaches can affect a team?
Another example.. look at Andrew Wiggins. When he was in Minnesota with a mediocre coach, he was considered a draft bust. Now he’s on the Warriors with an all time coach (Kerr) and he’s blossomed into an all star, the Warriors second best player, and one of their best defenders. So it tells you how much a different coach and system can affect the same player.