Now that the dust has settled following last weekend's horror show, it's more obvious than ever how important centre-backs are to the continuation of Rodger's 3-4-3 formation. During Sakho's absence we saw our build up play slow, affecting the entire side whilst against challenging opposition Emre Can's positioning and aerial weaknesses have been exposed; he's not a long term option at CB unless we really dominate possession. There are two clear criteria for centre-backs in a three beyond the basic expectation of being able to defend to some degree (sorry Dejan). We need composure on the ball and mobility. Now, Sakho is our best defender and exhibits these attributes. We should look to partner players with him. Skrtel has shown he can do well as the middle centre-back - his deficiencies of mind are covered by his fellow centre-backs and he's free to play to his (physical) strengths. Him starting is not a disaster, but he could be improved on - but it's not priority. We need to facilitate Can moving into midfield - he will be a star and we want him to stay here for a long time. Kolo should be cover/cup games only, which he does admirably; Dejan and Coates should ideally be gone; Ilori has promise but we need certainty; Wisdom I doubt will play for us again unfortunately. I'm going to suggest some 'realistic' candidates which I admire - these are also players we 'could' get without CL football. Key things I want in any signing this summer - signs of toughness, leadership, experience and versatility. For the record I'd take Howedes and Alderweireld. BENEDIKT HOWEDES One of our key failings as a team and defence especially is a lack of leadership. Howedes is a long term captain, experienced player in a good league + Europe. He has achieved huge success internationally. Crucially, he has shown he can perform at CB or RB at the highest level - this added ability to play would make him ideal. At 27 he's ready to arrive and perform. Would likely cost £15m+. VLAD CHIRICHES May seem a strange choice, but Chiriches may represent a very realistic option. Hasn't played much for Spurs this season and would surely take a move. By all accounts a capable player at CB or RB. At 25 has captained his national side during these qualifiers. Knows the PL. Would take him as a back up and would rather he starts than Can or Kolo. Would likely cost £10-15m however. Spurs + PL tax. TOBY ALDERWEIRELD Not exactly another Saints player, but one who has performed very well in the PL - likely to the annoyance of Liverpool and Spurs, clubs linked to him for several seasons. Doubt he will stay at Atletico without a guaranteed place. He may want a CL club move, but since he was willing to go to Saints he may move here if the deal is right. Can play CB, RB or in midfield. A lot of ability and composure - a player waiting to step up and be recognised at a top club. Has won leagues at Ajax, and has European, PL and international experience. Would cost £10m+ NICOLAS N'KOULOU Was a big part of Biesla's Marseille side before injury. Quite similar to Skrtel in that he's rather physical and plays a simple game, but has a little more class and mobility than the Slovakian. At 25 he has 51 international caps and has been in the Ligue 1 team of the season twice since 2012. Crucially, he is used to a high pressing style with Biesla and probably represents a cheaper option - his wages are not extravagant and the Ligue 1 to Premier League road is well-trodden for this reason. Would cost £10-15m. JOEL MATIP A team-mate of Howedes and an equally attractive player. At 23 he's already shown an aptitude at CB and in midfield. For being 6"4 (!!) he is very good with the ball for a CB. Would fit our style perfectly. However, if available he would surely be approached by several sides. Would cost £15-20m(+) JAN VERTONGHEN Perhaps the least likely player listed due to his current employers. Undoubtedly a great player when on his game - buckets of ability and composure. He is however left footed and unlikely to displace Sakho. Lots of experience in winning sides (Ajax), CL (Ajax) and in the PL (Spurs ). Would cost around £15m. FABIAN SCHAR Although a decent defender, Schar's most attractive quality is his contractual situation - his current deal runs out in the summer. Could be taken very cheap or indeed for free. Has been linked to numerous PL sides - Arsenal, Newcastle, West Ham and ourselves following his performances in the CL group stage. Has played for Switzerland since the Olympics and of course has experience winning things at Basel. Could cost NOTHING. EDER ALVAREZ BALANTA Possibly the most left-of-field option. Widely regarded as one of the biggest CB prospects world wide, Balanta didn't secure a move to Europe in the summer - despite his agent reportedly touting him to ourselves among others - was strongly linked to Barcelona also. Currently a starter for River Plate - not exactly a pressure-free environment - and has shown physicality, mobility but also skill on the ball. He is however left footed. Would cost around £10m. Possible work-permit issue but has played 5 times for Columbia in 2014.