The tall German with a big task: bring order to Gunners' defence

Per Mertesacker ticks boxes. For a club looking for a player to bring height, experience, defensive acumen and leadership the 6ft 6in, 75-times capped Werder Bremen captain offers a seemingly ready-made solution.

There is more to the tallest player Arsène Wenger has brought to Arsenal; he speaks English, is a popular and respected figure within his club and national dressing room, and an adroit reader of the game, as testified by a threadbare collection of nine bookings in 221 appearances in the Bundesliga. The suggestion from Germany is that he will have no problem adapting swiftly to the demands of the Premier League, nor the demands of living in a new country, an issue that Wenger has previously voiced concern over.

He is fit, too, which given Thomas Vermaelen's difficulties is another significant plus point. A summer break stretched by a heel injury that brought a premature end to last season has led to him returning notably refreshed and recharged. "I haven't felt this good physically in a year," he said after making his comeback in a friendly against Everton this month.

It is those claims of freshness that will reassure Wenger. For a relatively young player he has plenty of miles on the clock, having played in the last two World Cup finals and the 2008 European Championship. "He is a 26-year-old with the look and body of a 36-year-old," is how one Bundesliga observer puts it. And, some would say, the pace of a ponderous 36-year-old. Lack of speed and agility has been a constant criticism attached to Mertesacker throughout his career, both for club and country. His exemplary disciplinary record, as well as Germany's relative success during his tenure in the centre of their defence, suggests he has become able to compensate for any such failing through positional awareness and the instinct acquired over a seven-year international career.

The speed of the move came as a surprise. Mertesacker may have been a long-term Arsenal target, a move was first mooted last summer in the wake of the World Cup, but he had expected to stay in Bremen for another season. Thomas Schaaf, Bremen's manager, had recently awarded him the captaincy in succession to Torsten Frings.

Werder, though, have financial concerns and with their new captain's contract approaching its final year, the need to bring funds into the club won out. Bremen slipped to 13th in the Bundesliga last season, having finished third in the previous campaign, denying them any European income this season and accelerating the need to sell their best player.

Last season was a poor one for both club and player. Mertesacker's performance suffered as the team's form dipped, but it was not just the struggle of playing in a poor side that was behind his decline. He was barely 20 when he made his international debut in 2004 – handed a first cap by Jürgen Klinsmann in a friendly against Iran – and he soon became an integral part of a revitalised German side. In the 2008 World Cup they made the last four, in Euro 2008 they reached the final and last year in South Africa they went out in the semi-finals, beaten as two years earlier by Spain. That has meant a relentless schedule for Mertesacker and, rather like Wayne Rooney, last season brought a degree of burnout. "His poor form was a reaction to his body," says Philipp Selldorf of the Suddeutsche Zeitung.

Mertesacker comes from a footballing family – his father Stefan is a junior coach at Hannover, where Per began his career. He made his name as part of a defence playing in front of Robert Enke, the goalkeeper who was to become a close friend before his death two years ago. Aged 21, he won a place in Klinsmann's squad for the 2006 World Cup on home soil and he started every game as Germany exceeded expectations to reach the semi-finals, where they were beaten in extra time by Italy. After the penalty shoot-out victory over Argentina in the quarter-finals he was on the receiving end of an assault by Leandro Cufre that sparked a mass brawl on the pitch. Cufre, an unused substitute, felled the startled Mertesacker with a kick in the groin and, after a bad-tempered, tense contest, players from both sides quickly joined in.

Mertesacker's form in the finals helped earn him a €5m (£4.4m) move north to Bremen, which took him into the Champions League for the first time, and a first experience of English football. He scored the winner – and coped comfortably with Didier Drogba – in a group game with Chelsea, but his most recent entanglement with an English team proved less effective as he was part of a Bremen defence given the runaround on the other side of north London, Tottenham winning a group game 3-0 during their happy romp into the knockout stages last year.

That was part of a miserable campaign for Bremen and Mertesacker. He had missed the home tie against Spurs after breaking an eye socket during a Euro 2012 qualifier with Azerbaijan. When the season ended Mertesacker called on the club to bolster the squad – Mikaël Silvestre arrived, having been released by Arsenal in a move not likely to encourage the doubters to stay put. But Mertesacker still appeared in no mood to move on. When he was handed the captaincy, he spoke happily of doing the job for the "next 100 years" and when he left Bremen to link up with the national squad in Düsseldorf on Monday there was no suggestion he would soon be following in the footsteps of another friend, Michael Ballack, and heading for London.