With three rounds remaining in the regular season, Tigers are sixth in Betfred Super League, just two points adrift of Warrington Wolves, who are second, but only a similar distance ahead of seventh-placed Catalans Dragons.
The 24-0 win at Huddersfield Giants on Sunday was Tigers’ second successive victory and Ellis reckons they are in good shape to secure a play-offs spot.
“With three games left you never know what can happen,” he said.
“It’s very tight, but we play all top teams now so they are all four-point games.”
Tigers’ remaining fixtures are at league leaders St Helens, home against fourth-placed Hull and finally away to Wigan Warriors, who are third.
Ellis stressed: “We can’t worry about what anyone else is doing, it is just game by game.
“We are just taking each game as it comes and, hopefully, we’ll get three wins.”
According to Ellis, Tigers have taken confidence from their performance at Giants, particularly defensively.
He said: “It wasn’t pretty, it is always tough at Huddersfield.
“They are fighting against relegation and we are fighting for the top-five so it was always going to be tough, but we were glad to get the win.
“We were pretty happy with our defence, especially keeping a good side like them to nil, so overall we were pretty happy.”
Castleford led 4-0 at half-time, thanks to James Clare’s early try and added touchdowns by Adam Milner, Mike McMeeken and Jesse Sene-Lefao after the break.
Ellis admitted their performance on attack was “a bit scrappy”, but is confident they will become sharper as he gets more time on the field.
The game at Huddersfield was only his second of the season and he said: “It probably comes down to me a little bit in the halves, but that’s another game under my belt and, hopefully, I’ll be better next week.”
Ellis suffered a knee injury in pre-season and underwent two operations before making his comeback in this month’s home win over London Broncos.
“I’ve hardly played for 12 months so it is going to be tough,” he admitted.
“It was good to get another game under my belt, we’ve got this weekend off and then St Helens away which is going to be very tough.
“It doesn’t come easy at this stage of the season, but I am glad to be back playing.”
Ellis reported no ill-effects from his first two comeback matches.
“I’ve come through all right,” he confirmed.
“We have had a few injuries this year so I have probably been chucked in a bit earlier (than expected).
“I am just getting up to speed with everything, but, hopefully, I will be feeling a bit better next time.”
Super League takes a break this weekend for the Coral Challenge Cup final between Warrington and St Helens.
“It’s probably not a good thing for me, coming back to it,” Ellis said.
“I would rather play and keep going, but there’s nothing I can do about it.
“We’ll have a good week’s training then get back into it for the Saints game.”
Ellis required stitches in a head wound suffered against Huddersfield at the John Smith’s Stadium and admitted to being “a little bit sore”, but said he will be “absolutely fine” for the match at Totally Wicked Stadium.