Cardiff City return to the Championship this summer facing a challenge that is both familiar and entirely new. Promotion was secured in style under Brian Barry-Murphy, but League One success guarantees nothing in a division littered with former Premier League clubs, parachute-payment beneficiaries and teams capable of spending millions in pursuit of the top six. The transfer window opens on June 15 and, with staff reconvening next week, attention is turning towards what would constitute the perfect summer for the Bluebirds. And there is a balancing act to strike. Cardiff cannot - and don't intend to - simply rip up a squad that delivered promotion. Equally, standing still is not an option. The Championship exposes weaknesses ruthlessly and there are areas of Barry-Murphy's squad that need strengthening if Cardiff are to avoid merely battling for survival. The ideal scenario is becoming increasingly clear. Four key signings are being targeted this summer; a powerful midfielder, a winger, a left-back and a striker. Of those, the midfield role perhaps feels the most significant. Ryan Wintle's departure removes not only a key player from last season's side but also gives Cardiff the opportunity to reshape the entire profile of their midfield. Wintle's qualities were obvious, but the Championship demands a different level of athleticism and physicality. Cardiff have technical players in abundance. David Turnbull, Alex Robertson, Rubin Colwill and Joel Colwill all want possession. What they arguably lack is a physically dominant presence capable of winning duels, protecting the defence and helping the side become more effective at both attacking and defending set pieces. The ideal recruit would be an imposing No.6 who allows Cardiff's creators to flourish further forward. The need at left-back is almost as obvious. Joel Bagan enjoyed an excellent campaign and deserved his place in the League One Team of the Season, but Cardiff cannot afford to enter a Championship season with no genuine competition for his shirt. The last time Cardiff operated in this division, Callum O'Dowda made the position his own before subsequently moving on to Hungarian side Ferencvaros. Bagan has developed hugely over the last 12 months, yet Cardiff still need either an upgrade or a player capable of pushing him every week. Further forward, the return of Omari Kellyman to Chelsea has left a sizeable hole. Many supporters would welcome another loan move if one could somehow be negotiated, but Cardiff cannot plan their summer around that possibility. They need a winger who contributes goals and assists immediately. Ollie Tanner looks primed to play a major role after registering 12 assists despite missing a substantial portion of last season through injury. However, the opposite flank remains less settled. Chris Willock showed flashes, Cian Ashford continues to develop and Isaak Davies once again endured frustrating injury problems. Another wide player capable of meaningful goal contributions is essential. Then there is the striker position. Yousef Salech and Callum Robinson provide strong Championship-level options.