Oh my God it's nothing like that, you've completely glossed over the fielding issue (which given our recent crap fielding as a team it is a serious point of interest) and while Prasanna's batting hasn't clicked at international level, he clearly has far more class than Ajantha with the bat and is more likely to provide able lower support or a handy cameo than Ajantha.
Why don't you actually make an argument rather than pander stats, because you're choosing general stats that don't properly reflect the situation Ajantha will find himself in if he were to come into the team at some point during the world cup, let me explain...
The fast bowling has regressed rather alarmingly, even since the last time Ajantha played outside Asia in England, he probably won't have the benefit of early wickets to help him maintain economy against the good batting line-ups. To be economic in this WC, you need to be a wicket-taking threat or bowling in a low pressure situation such as after the loss of wickets because the pitches and fielding restrictions have made it impossible to contain simply by putting the ball on the spot, particularly when it skids straight on as in Ajantha's case. From our spin bowling ranks only Rangana Herath has the class required to remain threatening enough to keep the batsman on guard in these conidtions while also not giving up constant pressure-relieving deliveries, Satchi is an anomoly, where his defensive bowling (certainly before the remodel) was good enough in most conditions to remain economical despite not taking many wickets.
Ajantha Mendis takes a lot of wickets, leading to a reputation of being an 'attacking bowler', but that's a myth IMO, he benefits from mistakes because he uses many variations and is a player that teams are often forced to target, it's no wonder he's toothless in test cricket where the onus is more on the bowler to induce an error rather than simply try to outfox a batsman who needs to score quickly. However this is Australia/NZ with extremely flat wickets, batsman can hit through the line and mistime sixes with only 4 fielders on the rope and if they are playing SL not a huge threat coming from the pace attack, Mendis would get murdered at worst, milked at best.
Prasanna puts far more revs on the ball and his style is more genuinely attacking, meaning he'll have a better chance on containing the batsmen because he provides an attacking threat that batsmen will either have to guard against or be good enough to overcome it and go big anyway. And in any case he'd only ever play as a second spinner where secondary skills such as batting and fielding are pre-requisites to get the spot in order to balance the team.
Don't reply with stats