While Harrell is coming off a Sixth Man of the Year regular season, Ibaka is an upgrade in essentially every aspect. He is a far superior defender, stretches the floor on offense and has a career's worth of playoff success under his belt.
Here is a look at how the Clippers rotation looks after his signing:
Projected Starting Lineup
C: Ivica Zubac
PF: Marcus Morris
SF: Kawhi Leonard
SG: Paul George
PG: Patrick Beverley
Bench: Serge Ibaka, Lou Williams, Patrick Patterson, Luke Kennard, Joakim Noah, Terance Mann, Mfiondu Kabengele
The Clippers still have an obvious need at point guard, having failed to convince Rajon Rondo to join the franchise. Rondo instead agreed to a contract with the Atlanta Hawks, per Wojnarowski. Luke Kennard may be able to fill the role as a distributor off the bench, but he's been oft-injured throughout his NBA career and is not a lead ball-handler.
Despite still having a clear roster deficiency, it's easy to argue that Ibaka fills the need that ultimately knocked the Clippers out of the playoffs last season. Nikola Jokic dominated Zubac and Harrell in particular, essentially playing the latter off the floor.
Ibaka should be able to hold his own in the playoffs against most big men while also keeping the floor well-spaced. The Clippers' "best five" lineup will feature five players who shot above the NBA league average from three-point range last season while posing no obvious defensive weaknesses.
These Clippers have to prove they can withstand the postseason pressure, but they again look to be the best team in the NBA on paper heading into next season.