"It was really amazing to be back home."

During his whirlwind 16 months at the club, Jeremie Frimpong captured the hearts of many within Scottish football for his honest, enthusiastic, and infectious post-match interviews. Those sentiments came rushing back for many on Thursday night as the ever-beaming Frimpong gushed nothing but praise on Celtic, the supporters and his former home.

The Netherlands U20’s star left Parkhead at the end of January, when the club were experiencing some of their most troubled days of last season’s campaign. The move to Bayer Leverkusen left many a Celtic fan surprised and annoyed. If you can cast your mind back to those tumultuous days, you’ll remember that rather quickly, Frimpong become the fall guy, someone to point blame at.

How dare a young talent who Celtic have gifted an opportunity to, leave? He’s not even the complete player, he thinks too highly of himself. He has no respect for the club with comments such as, "Celtic are a much less attractive option for youngsters these days." Those were the sort of statements that were flying around at his departure.

A gamble, for sure, for both parties – Frimpong and Bayer Leverkusen, that is. An undisclosed fee, believed to be in the region of £11.5million was – and still isn’t – a gamble of any kind for Celtic. I can’t believe I am going to say this, but it was actually a terrific piece of business by the club, considering he was bought for well under a million quid.

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Frimpong checked out of Glasgow far from the finished product. Towards his final few months with the club, the early excitement and promise he naturally oozed diminished, instead of becoming enhanced.

His pace was forever frightening and damning for any opposing player, but for Celtic supporters, the performances rapidly became frustrating.

Deployed as a right-back – as he was for Bayer Leverkusen - he failed to defend with any real conviction, desire, or robustness when in the green and white hoops.

When pushed slightly higher into a right-wing-back role, defensive duties were far from the forefront of his mind. In an attacking sense, he repeatedly beat his man but almost froze at the sight of the byline and consistently found himself searching for a bigger pitch.

Shoved even further forward into a left-midfield position, albeit rarely, his inability to cross a ball with any real quality ultimately called time on that experiment.

So, what has changed in the last eight months? Because that is all that has passed since the 20-year-old Frimpong scooted out of Celtic Park. However, the 20-year-old Frimpong who reappeared out of the tunnel and dawned the park of Paradise, was a very different character.

He’s in a better team. That is abundantly evident. Players – Frimpong – improve when surrounded by talent, it rubs off and he is a young man reaping the rewards.

But technically, individually, his progression over this short period of time is scarily high. Admittedly, I’ve only caught Bayer Leverkusen on the odd occasion this season, but  those who watch Frimpong on a regular basis would seem to agree.

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Kudos cannot only be given to his teammates. The coaching, teaching and encouragement he is receiving in Germany is undoubtedly of a greater, more rounded level than what he received in Scotland.

Up against Jota, Frimpong comfortably saw the ball out for a goal kick with confidence. A task he struggled to complete at Celtic. Often outpowered and outwitted. Not now.

A sight rarely to be seen before on the East End of Glasgow – Frimpong delivering perfectly-placed crosses into the danger area. A genuine threat from the wing.

The emotions are mixed. Pride in seeing a kid grabbing a lucrative opportunity with both hands, blossom. But again, frustration. Because many a Celtic fan knew this level of player was within Frimpong, Celtic just weren’t getting it out of him.

Bayer Leverkusen offered the young Dutchman a lifeline, to abandon life in Glasgow before his surroundings stalled his chance at development.

How many more Frimpong’s have there been?

And worryingly, how many more are there to be in the future?