Arsenal have just confirmed the sale of Gabriel Martinelli to Al Hilal, leaving their attacking depth significantly weaker before the January transfer window reopens next year.
According to BBC Sport, Martinelli's transfer fee could reach as high as £60 million. This figure highlights what is described as Arsenal's previous decision-making mistake — they could have signed Antoine Semenyo for £65 million earlier this year, but ultimately took no action.

The ideal target they missed
Semenyo was in excellent form at Bournemouth during the first half of last season and continued to perform well after moving to Manchester City. The Ghana international scored 10 goals for the Cherries last season and added another 11 after joining City, finishing with 21 goals in total, level with Arsenal forward Viktor Gyokeres' final tally across all competitions.
According to The Athletic, Semenyo himself is an Arsenal fan and would likely have been happy to join. talkSPORT also reported at the time that Arsenal were considering Semenyo, but wanted to complete player sales before making a move, possibly due to financial limitations.
However, reports later suggested that Arsenal had the financial ability to pursue top-level players during the summer. The contrast between the two situations made the club's approach difficult to understand.
The market has changed dramatically
Since then, transfer market prices have surged. Players of a similar level, such as Morgan Rogers and Bradley Barcola, have commanded fees close to double Semenyo's previous asking price. Therefore, the £60 million received from selling Martinelli may now have much less purchasing power.
If Arsenal had activated Semenyo's £65 million release clause at the time and then sold Martinelli a few months later, they could have completed a major upgrade on the left side with a net investment of only £5 million.
Arsenal were similarly hesitant in the pursuit of Rogers and were eventually beaten to the signing by Chelsea. They are now forced to search urgently for reinforcements in an inflated market.
Lesson: The transfer market requires more decisiveness
Months later, looking back at Semenyo's £65 million price tag, it appears to have been an excellent value for a world-class player. Given that Arsenal ultimately sold Martinelli in the same year, missing out on this deal can be viewed as a major setback — they could have secured an ideal replacement and upgrade at a very low net cost.
Of course, hindsight is always easier. But if Arsenal fail to learn from this experience, they may pay an even greater price in the transfer market in the future. They ended the summer with a thinner attacking line than last season — and attacking weakness was already a clear issue for the team last season, despite ultimately winning the Premier League title.