1) dedicated servers should sort out most types of lag problems for the most part, the elpresador ''lag switcher exposed'' video showed us that the current p2p system is unnacceptable in 2013
2) even offline i noticed the timing sync between players is a little off, somebody is always a millisecond or two ahead of some1 even in offline local match. Also it seems all bullets dont register even offline at times as well, spawns are just flat out illogical and framerates dropping in offine matches is a problem too. they gotta sort these things out or its not gonna transition well online.
3) combine/buff/add certain perks, tactical mask and flak jacket together, ghost and hard wired together, blind eye and cold blooded together, give engineer the ability to hack non scorestreak equipment like claymores/betties/charges e.t.c, dexterity and fast hands together, extreme conditioning and lightweight together, awareness and dead silience together, give scavenger the ability to replenish one noob tube at a time, buff hardline so u get 5 extra points for killstreak kills and 50% more score for uav/counter uav/vsat/guardian assists, also award them 10 points for getting assists with a killstreak, like if u get a himarker with a lodestar/chopper and ur teammate finshes off the target afterwards. give toughness the ability to make enemies flinch 5% more, bring back recon pro from mw3 (30 seconds on radar), bring back a nerfed danger close pro from mw2 but instead of increasing damage increase lethal radius of explosive weapons/scorestreaks by a worthwhile/noticable but not overpowered margin (about 20% maybe?). Thats 12 very powerful perks for different strategies (4 for each tier) that would give this game more of a cod 4 feel, i like them all so i dnt see people crying too much about one in particular because they are all overpowered and thats a good thing . when everything is powerful, nothing is powerful
4) general changes i would make to bring skill/tactics back to the game: i would tone down flinch 7%, i would make sensor grenades show enimies hit by them to your entire team for 1 minute (1 minute and 30 seconds when used with recon). i would remove the delay on dropping prone, i would remove the hipfire to ads delay that prevents you from shooting exactly where ur recticle is pointing the splitsecond u ads, all guns will kill with 2 or less bullets to the head within their effective ranges, headshots would always matter somehow! i would undo the hipfire nerfs on the smgs and buff the hipfire on the other weapons at least by 5 percent, laser sight will also be more accurate slightly for all weapons but drasticly buffed for snipers, snipers would lose the ability to quickscope (no pinpoint accurate kills without even fully looking down the scope!) but they would be able to get pinpoint no scopes at very close range much easier with a laser sight. silencers wouldnt affect snipers at all either. quickdraw would also help lmgs a bit more than it does now and air scorestreaks will have no more than 1 flare. penetration would be better for lmgs/assualt rifles. other changes specific to weapons will be mentioned next.
5) s12, m1216, and the executioner would kill in one less pellet and have their range buffed about 4 meters, r870 would have is nerf undone and re nerfed so that its damage dropoff kicks in 1m sooner and nothing else, ksg will have a extra meter of 1 hit kill range, kap40 and b23r will have 18 bullet mags and be able to kill with 2 headshots up close, tac45 will have 10m of 2 hit kill range, five seven will have 5m of 2 hit kill range and take only 5 bullets outside its range, crossbow will have a 5% lethal radius increase, smaw would shoot perfectly straight, msmc will have its recoil un-nerfed and its range increased by 5m, pdw will have its recoil un-nerfed and its range increased by 5m as well, mp7 and chicom (burst) will have 6m of 3 hit kill range, vector would have 5 meters of 3 hit kill range and the skorpion will have 4 meters of 3 hit kill range. the hamr and lsat would have a unlimited 4 hit kill range after their 3 hit range, the qbb will have its 3 hit range increased by 4.5 meters, the mk48 would have unlimited 3 hit kill range, the m27 would have 14m of 3 hit range, the type 25 would have 10m of 3 hit kill range, the scar would have its recoil reduced by 20% and have a unlimited 4 hit kill range after its 3 hit kill range, it will also be able to kill with 1 headshot and 1 additional shot anywhere else within its 3 hit range, the mtar would have 20m of 3 hit range, an94 would have 30m of 3 hit range, fal would have its recoil un-nerfed and its 2 hit range buffed 2m, smr would have its recoil reduced 12-15%, have its mag size increased to 25 and it would kill with 1 headshot anywhere inside its 2 hit kill range, m8a1 on burst would have 17m of 3 hit range, headshots would actually matter and its mag size would be returned to 36, swat on burst would kill with 2 bullets for 25m, ballista and xpr50 would kill 1 shot anywhere above the stomach but not including the arms, dsr would 1 shot above the waist not including arms, the svu will have its sway reduced 5% and be able to 1 shot to the neck. once again, when everything is powerful, nothing is powerful.