They weren't part of a cohesive strategy, same reason signing JT was a bad move.
Both teams needed to get tougher and stronger on defense, adding another offensive weapon didn't make them a better PO team.
Notice how often offensive oriented teams have big regular seasons (blowing out bad teams on a regular basis) but struggle in the playoffs?
Florida plays an aggressive offensive system that gives up a lot of scoring chances the other way, but they were a soft team last year, Giroux bless his heart, wasn't the solution, he was a luxury item for a team that didn't have a problem scoring. Chariot was just a bad move, Risto bad, had a horrible playoff and didn't play as well as Risto this year on a better team, CF 41.82%, xGF 42.39%. Overpay for a RHD.
Tkachuk was a good fit for Florida, but Zito's hands were tied due to the Cap, had to let Marchment walk, signed Eric and Marc Staal to the vet minimum, Cousins 2yr/$3M, Colin White $1.2M, got Mahura D and Lyon off waivers. While getting to the Finals was luck, keeping the team competitive was skill.