Trading Ariza for an upgrade at the 3 spot would be more important at this time but if there is an opportunity to upgrade at the 2 spot then of course Martin is expendible. That being said, what other 2 guards in the league would be much more of an upgrade... Kobe, Wade, Roy... and thats about it. If you are Morey you look to move Ariza or Battier first, then you have to weight the balance on whether giving up Martin hurts us more than the aquisition. At the 3 spot there are several key players we could upgrade our team with. But the only one that would be worth giving up Martin for would be Melo.
No, Chase and Taylor would be enough to fill the void left by Martin. Martin was a slasher player too; he drew fouls like crazy how? By slashing. Taylor was pretty good in Summer League; he deserves another chance.
Martin is going to be the definitive "production" player this season; no NBA star will score as many points on so few shots. Like I said earlier, his best season ever, possible all star, book it.
Chase isn't getting minutes at the 2 and he's an important part of the 2nd unit, so he's not replacing Martin. Taylor hasn't shown that he's ready to start at the 2. Getting rid of Martin weakens the bench rotation and takes 20ppg out of the starting rotation. His only possible replacement is Brooks, who probably also goes in this deal. Morey needs to find a 2 somewhere else to make this deal, becasue we don't have one now.
There are very few differences between SG/SF and you are overvaluing them. On defense, the biggest issue is size and speed, but this is not an issue since Martin is a Matador. But if by trading Martin, you keep Battier & Ariza, then that is not an issue as both have enough size and either guile or athleticism to check fast SG's. On offense, having good ball handling and the ability to drive in your SG is ONLY necessary if your offense is predicated on him being the centerpiece of your backcourt offense. If losing Martin is done in a transaction that lands CP3, or even Melo or Granger, then that the offense implications of losing him are not that bad. That super star you are bringing to the team would become the offensive centerpiece of the backcourt and you are asking him to create the offense within the system. As a result, as long you can find a SG who is around average in all areas, or perhaps is stellar in either 3pt shooting or defense, then you are okay. That replacement would not be as good as Martin, but you do not need them to be as that position becomes more of a role player. In this sense, moving Ariza to the SG is not a death-knell. He could play defense at the position because he already often checks SG's. He can hit a shot once in awhile, and if he is now at SG, maybe he can learn to use his size to post up smaller SG's. An assumption would be that by trading Martin, we would not be trading Brooks. If the trade were to get a Melo/Granger then this would work perfectly. If the trade were to get CP3, then we would have to start Battier at SF and have Budinger back him up. If we could get another SF/SG it would work but it is not the end of world. Also Taylor could get spot minutes at the SG, and there could even be the possibility of playing Lowry & CP3 in the backcourt together as RA has already shown to like playing AB & Lowry together at times.