Bardi vs Di Gennaro is a very interesting discussion, especially because both players exhibit tremendous promise for the future No.1 shirt at Inter.
Imho a general scouting analysis of a goalkeeper should focus on goalkeeping technique, physique, leadership, and on the ball skills.
On goalkeeping technique, Bardi possesses exceptional reflexes. Di Gennaro likewise has VERY strong shot stopping capabilities, but his catching and ball handling technique is very poor (although I have seen an improvement with Cittadella). One of Bardi's best attributes is his mobility in the box, and a strong sense of anticipation. His jumping ability is also VERY strong, and imo overall he's a superior goalkeeper technically speaking.
However, Di Gennaro is much better than Bardi in coming out for crosses, and his conceded goal against Inter is a testament to the necessity of improvement in this area. However, it should also be noted that Bardi makes much more of an effort at holding on to the ball, rather than just pushing it away, which is a VERY important attribute.
Di Gennaro is also quite effective at employing at his legs and feet in the shot stopping process. It's clear that both players are fairly raw atm (although Di Gennaro is much more undeveloped than Bardi).
Moreover, while Bardi is taller than Di Gennaro, the latter utilizes his physique much more than the former in his style of play. Both keepers also possess strong balance.
Di Gennaro seems like more of a leader on the pitch than Bardi, and it's especially reflecting on the latter's poor communication skills (which glared in Livorno's defeat against Hellas Verona). From what I've seen of Bardi in Serie A, he needs to develop the ability to organize his defence.
Generally speaking I'd say that Bardi is more promising than Di Gennaro, but I wouldn't end the discussion there, especially when I see Di Gennaro beating Leali to the 2013/14 Serie B GK of the year award (if he keeps up his great performances with Cittadella).
Improvement in the last category is necessary for both prospects. Both are generally poor at goal kicks, although Bardi seems to be stronger in this area. Di Gennaro generally lacks composure on the ball, although I've seen some improvement in his spot kicking accuracy at a Serie B level (compared to what I've seen of him with the Primavera).
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In terms of positional awareness Di Gennaro is superior to Bardi
Di Gennaro is also very effective at making himself "big"; in providing a large target for attackers (especially in 1v1 scenarios). He also has very good "judgment" in timing challenges and when to come off the line.
I see a lot of Van der Sar in Di Gennaro, and more of someone like Zoff or Marchetti in Bardi tbh