Manuel Pellegrini is likely to remain as Manchester City’s manager for next season after the club’s hierarchy reviews the Chilean’s performance, a process that will also involve looking at the signings made by the director of football, Txiki Begiristain, and progress under the chief executive, Ferran Soriano.

City are known to be keen on attracting Pep Guardiola as their coach but the Spaniard has said he intends to serve at least his current contract at Bayern Munich, which runs to the end of next season, which is when Pellegrini’s expires.

The City manager has credit for winning the Premier League and League Cup in his first season and the now-guaranteed qualification for the Champions League this time. Four straight victories, including Sunday’s 6-0 win against Queens Park Rangers, have improved perceptions of this season and the squad, after the spring wobbles which included 1-0 away defeats to a Lionel Messi-inspired Barcelona and Burnley, and losing 4-2 in the derby to Manchester United.

The end-of-season reviews, a routine practice of City’s Abu Dhabi-based chairman, Khaldoon al-Mubarak, will nevertheless analyse the club’s recent recruitment and aim to improve on it this summer. Since the summer of 2013, under the two former Barcelona executives Begiristain and Soriano, City have spent around £141m on Eliaquim Mangala, Jesús Navas, Álvaro Negredo, Stevan Jovetic, Fernando and Fernandinho, before January’s £28m signing of Wilfried Bony, none of whom are widely considered to have made an improvement worth the outlay of cash.

Before Begiristain arrived, Brian Marwood, the former Arsenal winger, Professional Footballers’ Association chairman and Nike employee, had in effect done City’s director of football job. He believed in retaining a core of English players, alongside signings that included Yaya Touré for £24m in 2010, David Silva for £26m the same summer, Sergio Agüero for £38m in 2011, and other mainstays of the 2012 and 2014 Premier League-winning squads.

Yet City are also mindful of the 2012 summer, when they declined to sign Robin van Persie, who then won the title with United, and instead bought Jack Rodwell, Scott Sinclair, Javi García and an ageing Maicon, players all wanted by the then manager, Roberto Mancini, but now seen to have not been of the required calibre. Modern football’s transfer dealings are recognised to be inherently unpredictable, with agents and ownership issues having to be negotiated. The Begiristain signings now under scrutiny, due to a season without a trophy and the Champions League exit to Barcelona, are at least considered close to top rank.

The stand-out question mark, of course, is the one against Mangala. Club sources have confirmed that City paid £42m last summer for the then 23-year-old, whom Porto had signed for £4.7m from Standard Liège three years earlier, and who had played in four friendlies for France.

In December 2011 Porto had sold one-third of Mangala’s economic rights for around £1.8m to Doyen Sports, an investment fund registered in Malta, which has anonymous investors. So, when Begiristain and the City board plumped for Mangala as their best prospect for the crucial position of centre-back, Doyen Sports received £14m of the total £42m, a £12.2m net profit in two and a half years to the unknown investors.

Another 10% of Mangala, which was bought out, because third-party ownership of players is banned in the Premier League, was owned by a company called Robi Plus, registered in England. The sole director is Mauricio Delmenico, a Swiss resident. Robi Plus received £4.2m of the £42m and now, without having filed its 2013-14 accounts, Delmenico has applied for the company to be struck off the register. Adbell International, the accountancy firm presenting the striking out application, did not respond to questions about it from the Guardian.

City had already dealt with Doyen in Begiristain’s first summer transfer window, 2013, when the club signed Navas and Negredo from the Spanish club Sevilla for a combined £34.9m. Sevilla were in financial difficulties, like many Spanish clubs below the two giants, Barcelona and Real Madrid, who devour so much La Liga TV money. Doyen began to provide funding for Sevilla and other clubs, mostly in exchange for promising players’ economic rights, and in 2012-13 Doyen Sports became the sponsor of Sevilla.

Neither Navas nor Negredo, both Spain internationals, are understood to have been part-owned by Doyen but the latter was represented by Doyen. It announced on 17 October 2013 that the Negredo transfer was one of its deals in a “busy summer” which also included Geoffrey Kondogbia’s move from Sevilla to Monaco, Radamel Falcao’s from Atlético Madrid to Monaco, and Kaká’s, from Real Madrid to Milan.

The agent acting on Mangala’s move was the ubiquitous Portuguese dealmaker Jorge Mendes, whose extraordinary summer 2014 included Ángel Di María’s and Falcao’s moves to Manchester United, James Rodríguez going to Real Madrid and Diego Costa signing for Chelsea. The £42m City paid for Mangala did not include Mendes’s agent’s fee. Clubs do not disclose individual agent’s fees, only the total paid in a year; in 2013-14 City paid £12.8m in total to agents, third highest after Chelsea, who paid £16.8m, and Liverpool, £14.3m.

Surprisingly, Mendes was not the agent in City’s £12m purchase of Fernando last summer, despite coming from Porto, Mendes’s original base of influence. The Brazilian midfielder, who has played in all four of City’s consecutive recent victories and made 22 starts this season, was represented by another Portuguese agent, António Araújo. His agency, Onsoccer, owned 20% of Fernando’s economic rights, so was paid £2.4m out of the £12m City paid for the player.

Fernandinho, the Brazil midfielder signed in the summer of 2013, generally reckoned to have been the best-performing of the players bought under Begiristain, was 28. City paid £30m for him to Shakhtar Donetsk, the Ukrainian club where a number of Brazilian players are signed, hoping for a big-money move to one of Europe’s major leagues. Fernandinho’s agent, unusually, is a woman, Daisy Brandino, who gained her early experience as a banker for wealthy private clients at a Swiss bank in Zurich.

Jovetic, who has made 43 appearances, including as a substitute, since City paid £22m for him in summer 2013, came from Fiorentina, as did the centre-back Matija Nastasic, who was signed the previous summer before Begiristain arrived, when Roberto Mancini was City’s coach. Jovetic and Nastasic, who is on loan to the German club Schalke, are understood to have been represented by the same agent, well known in the Balkans, Fali Ramadani.

When these signings and their performances are assessed by Mubarak, a senior Abu Dhabi political and business figure, the outcome is not expected to be damning. There is likely to be a recognition that football itself has changed since Sheikh Mansour’s £1.152bn investment in City fuelled the club’s rise and ability to sign elite players; fees are expensive and competition fierce among the top Champions League-competing clubs. Although £42m looks a very high figure to have paid for Mangala, he is still only 24 and has time to improve.

The result of their recruitment is that City now have several players expected to be offered for sale or exchange this summer, while the club targets a select few top players, including Paul Pogba from Juventus and Kevin De Bruyne from Wolfsburg, who they believe can make a stronger impact for Pellegrini.