Whilst the likes of Craig Gordon, Jason Denayer and John Guidetti grabbed the headlines last year, some of Celtic's summer transfer business hasn't reaped any rewards.
Mubarak Wakaso, Aleksandar Tonev and Stefan Scepovic have all struggled to make an impact this season, whilst one player isn't even at the club anymore.
Playmaker Jo Inge Berget played under Celtic boss Ronny Deila in Norway, hitting eight goals in 31 appearances for Stromsgodset.
Once on the books of Udinese, Berget was touted as one of the next big things in Norway, but in 2011 he left Udinese for good, joining Molde - and with 17 goals in 63 games, Berget made a big impact under Ole Gunnar Solskjaer.
In fact, Berget ended up following Solskjaer to Cardiff City in January 2014, but after just two appearances, he linked up with Deila again at Celtic, penning a season-long loan deal.
Again though, Berget struggled to make an impact in British football, playing just eight times, and whilst he scored two goals, Celtic cancelled his loan deal in January before Cardiff terminated his contract altogether.
Now back in Scandinavia with Swedish side Malmo, 24-year-old attacking midfielder Berget is trying to rebuild his career - and so far, he's doing just that.
Malmo played their first game of the season on Monday, beating Sundsvall 4-1 away from home, with Berget bagging the first two goals inside 16 minutes.
It's unfair to say that Celtic made a mistake over Berget and should have been more patient with him, but Berget is now trying to prove everybody wrong in Sweden. Two goals on his debut for Malmo is not a bad way to start.