Expectations were high after narrowly missing out on Champions League football last season but Everton have failed to live up to the hype, flirting with relegation from the Premier League at times in 2014-15.
Everton were hovering dangerously close to the drop zone before back-to-back wins over QPR and Newcastle United helped Roberto Martinez's men steer nine points clear of the bottom three prior to the international break.
Osman admits this season has came as a shock but the 33-year-old is already targeting a top-four finish in 2015-16.
"If we just take the league, then I could not have imagined the difference between this season and last," Osman told the Liverpool Echo.
"We had a great season last season with a record points tally and the team was positive and very confident.
"There's a few - not excuses - but reasons.
"We were so full of confidence going into the start of the season that we went out and attacked teams and we kept getting sucker-punched.
"We would dominate teams, have 70 per cent possession for the first six or seven games of the season but we'd lose a sloppy goal and concede where we weren't expecting.
"Teams were just trying to hit us on the break but we would've worked that out after six or seven games but then Europe started and the extra demands that brings."
Osman added: "I do think we are good enough to make the top four next season.
"We were disappointed not to get in the top four last season and I think the demands of having had such a good season meant teams were coming here hoping to nick a point.
"That was the first thing we had to learn this season and is something we eventually have learnt. It's about being patient because teams have just been coming to try and nick a point.
"Hopefully we can hit the ground running next season and we can be as good as we were last season."
