Arsenal have signed Real Madrid's "second-best player", according to Cesc Fábregas, while the Germany manager, Joachim Löw, has described the Spanish club's sale of Mesut Ozil for £42.5m as "incomprehensible".

Arsène Wenger and Arsenal continue to celebrate their deadline-day coup, with Ozil becoming the club's record signing and the third most expensive in Premier League history, behind Fernando Torres and Carlos Tévez. The excitement is palpable before Ozil's debut at Sunderland on Saturday week – he will first play for Germany in the World Cup qualifiers against Austria and the Faroe Islands – but the reaction in Spain and Germany has been one of shock.

Fábregas, the Barcelona midfielder and a former Arsenal captain, echoed the sentiments of many of Ozil's former Real team-mates, although he is pleased that his old club, where he played for eight seasons, have completed such an eye-catching piece of business. "I was really surprised by Ozil's departure," Fábregas said. "He seemed to me to be the second-best player at Madrid, after Cristiano [Ronaldo]. He'll be great for Arsenal."

Löw picked up on the sense of dismay inside the Real dressing-room and name-checked the Germany midfielder Sami Khedira and Ronaldo as being among those that were upset. Löw said that he would not have sanctioned the transfer if he had been in the shoes of Carlo Ancelotti, the current Real manager.

"Many Real players like Khedira or Ronaldo are sad about the transfer," Löw said. "For me, it's incomprehensible that Real would sell one of their top scorers."

Ozil had said last week that he would stay at Real, that he did not want to leave, but the situation changed sharply over the weekend when it was made clear to him that he would not be central to Ancelotti's plans. The arrival of Gareth Bale and, perhaps more pertinently Isco, meant that his opportunities in attacking midfield stood to be restricted. "I realised I did not have the faith from the coach or the bosses," Ozil said, in an interview with the German football federation's website.

Löw, however, believes that the transfer to Arsenal and the opportunity to work with Wenger will benefit the 24-year-old. "Mesut is a sensitive player and he needs the faith from the club and the coach," Löw said. "It seems that was no longer 100% there at Real, whereas Arsenal and their coach, Arsène Wenger, pulled out all the stops to get him.

"He has a top coach there and with Lukas Podolski and Per Mertesacker, he has two German colleagues. Arsenal are a strong team and they play technical, high-quality football."

Löw added that the transfer had not affected Ozil's preparations for Germany's matches. They are five points clear at the top of Group C, with four matches to come, and look certain to advance to the finals as the group winners. "Mesut looks perfectly happy and satisfied," Löw said. "He is fully focussed."

Wenger has named Nicklas Bendtner in his squad for the Champions League group phase. The Dane, who has one year to run on his Arsenal contract, did not complete a transfer as had been expected before Monday's deadline, with his wage demands proving to be one obstacle.

Bendtner, though, claimed that he had reached an agreement elsewhere only for Arsenal to block the move after their failure to sign the striker Demba Ba on loan from Chelsea. There is no room on Wenger's 25-man list of senior players for another forgotten striker, Park Chu-Yyoung, or the injured Abou Diaby.