The result sees McLaren falling further behind Alpine to fifth place in the Formula 1 Constructors' Championship, which saw their rivals claim a fourth and sixth position finish by drivers Esteban Ocon and Fernando Alonso.
This now means that Alpine leads McLaren by 13 points with four races remaining.
"It was a disappointing Sunday afternoon for us," Seidl said after the race in Japan. "On Daniel's side, despite moving up some positions at the initial start we were too conservative at the restart, staying out for too long which resulted in losing positions and dropping out of the points.
"On Lando's side we unfortunately lost several positions at the initial start which we then recovered by pitting at the right time following the restart.
"Overall, we were not as competitive as we would have liked to be," Seidl conceded. "We will now use the time we have before Austin to see how we can extract more.
"Thanks to the entire team here at the track, back home and HPP for completing an intense double header. I'm happy for the great Japanese fans that got to see some racing in challenging conditions. Also, congratulations to Max for his second World Championship," he added.
In his post-race interview, Ricciardo admitted he was happy they were able to race in the wet treacherous conditions.
"I'm happy we got to race today. "It was looking very unlikely so, as a driver, of course, to have that opportunity and have a bit of fun, I enjoyed that, and more so for the fans, especially sitting out in this weather," Ricciardo said.
"The end result was just really a case of when we fit the Inters, which was tricky," Ricciardo added. "It's not like a normal situation where it's ready and you just go. There are a few things to consider.
"I think the cars that went in, like Vettel certainly capitalised, so that's where we lost out today. Otherwise, I don't think our pace was too bad but it was also just a case of managing the tyres. We have some things to improve but ultimately, I'm just glad we made a race for the fans today.
"Congratulations to Max on winning a well-earned second Drivers' Championship."
Norris admitted the race was tricky having started from tenth on the grid but treacherous conditions forced him to be cautious early on and lose places, but thanks to a well-timed pit-stop he was able to improve and grab a point for McLaren.
"Firstly, I'm glad we got a race today," Norris said after the race. "The Japanese fans have been amazing here all weekend, and they waited in the rain for ages, so I'm glad we could give them that.
"Of course, as drivers we always want to race. The race itself was a tricky one. I lost a lot of positions in the first start which was unfortunate, but then made up for it with the pit-stop, and it was good to come away with a point.
"Finally, congratulations to Max on winning a second World Championship," Norris added.