The Sky Blues confirmed the signings of Michael Gault, Stephen McAlorum and Emmett Friars on Thursday night.
The experienced trio have all agreed one-year deals at Warden Street and Jeffrey is delighted with his business so far.
“Supporters could see that evidently we strove last season to give youth a chance, but also as important is for a balance between youth and experience,” he told the club’s official website.
“Significantly we also wanted to add experience, not just in terms of playing in big matches, but also in winning trophies.
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“Obviously this year we won our first, and got to Europe, and now we want to cement that achievement by adding experienced players such as the three we’ve brought in.”
Allan Jenkins may also be turning out for the Sky Blues again next season after Jeffrey confirmed he had offered the Scottish midfielder a new deal along with defender Caolan Loughran.
“We have made an offer to Allan,” said the Ballymena boss.
“Understandably he wants to take time to discuss it with his wife and family and will advise club in due course.
“Caolan has signed a new two-year contract.
“I’m delighted to see a young player like him commit his immediate future here and he is exactly the sort of player that will be able to learn and benefit from the new signings this season.
“After the excitement of last week, I think it is important to manage expectations now. It is tremendous that we’ve qualified for Europe and the financial rewards that will come, but don’t think it’s arrived at the door just yet.
“In fact, due to the salary cap system in place, we’ll not realise the full benefits until next season in all honesty. Therefore we continue to work with much the same budget as last season.
“But overall we are delighted to strengthen the squad in way we have.”