Arsenal have made some big-money signings in recent years, but some have not worked out the way the Gunners would have wanted to.Arsenal's five worst big-money signingsMikel Arteta's men perhaps had a bit of a tough spell in the transfer market after their new stadium was constructed. But they have not shied away from signing players on big transfer fees in recent years.On that note, let’s take a look at five big-money signings who have failed at Arsenal:#1 Shkodran Mustafi - €41 millionShkodran MustafiShkodran Mustafi arrived at Arsenal in 2016 with a lot of fanfare, as he had done well for Valencia and was a part of Germany's 2014 FIFA World Cup-winning team.However, the German failed to put in consistent displays and had an error-prone spell at Arsenal. He was a pale shadow of the player who flourished at Valencia.The speed and physicality of the Premier League were a bit too much for Mustafi; he was often found making the wrong decision or being out of position more often than not.After four indifferent campaigns at Arsenal, Mustafi was allowed to leave for Schalke on a free transfer in January this year. He is currently trying to help his club avoid relegation from the Bundesliga.So ends the Mustafi era at Arsenal. Horrendous signing. Had some good games, but up there with one of the most costly errors of judgement the club has ever made.— Charles Watts (@charles_watts) February 1, 2021#2 Henrikh Mkhitaryan - €35 millionHenrikh MkhitaryanArsenal signed Henrikh Mkhitaryan through a swap deal that saw Alexis Sanchez leave for Manchester United, but it turned out to be a costly transfer for the Gunners.While Sanchez was perhaps their best player at the time but was looking for a move out, Mkhitaryan had a poor spell at Manchester United and never really settled in England.Mkhitaryan showed glimpses of his ability for Arsenal, but he could never recapture the form that earned him a spot in the Bundesliga team of the season in 2016 while he was with Borussia Dortmund.The Armenian scored just nine times in 59 appearances for Arsenal, and was sold to AS Roma as the Gunners strived to minimise their losses.Since joining the Serie A side, Mkhitaryan has somewhat rekindled his old form, having scored 20 goals in 53 appearances already for the Giallorossi.Henrikh Mkhitaryan is having a truly remarkable season. Didn’t work out for him at Arsenal but 9 goals and 8 assists in his 20 Serie A games this season proves how good he can be.— Ben Rogers (@brogersjournal1) February 8, 2021