Vucinic's best record in serie A was set exactly when he played for a weak team (Lecce). Many times it's easier to score more when you're the focal point of a team than in a team where you're just another player.
Even more, Vucinic spent big part of his career far on the left from the box, while Quag was a pure striker.
Fabio Quagliarella is a 29 year old who plays his 10th season in serie A as a striker and his best season record is 13 goals in 35 matches. He has absolutely nothing over Vucinic. He doesn't score more, he assists less and he's much less versatile. It's easy to talk when Vucinic is living through a terrible form but the current (passable) form aside, it's not even a competition between those too.
Vucinic is only a year younger than Quagliarella, and hasnt exactly set the world on fire. Also, id just like to point out that Quagliarella is NOT in his tenth season in Serie A. He debuted for Torino in 2000, when he made no appearances for the club, i think he played a handful of games the season after before being sent on loan to a Serie C1 club side. Even on his return to Torino, they were in Serie B. His first true run in the league happened in in 05-06 with Ascoli, after which he played with Sampdoria, followed by two seasons with Udinese. Then Napoli and finally Juventus, where he scored 9 in his first season in 17 appearances, and could've easily had more if the injury hadn't happened. Compare that to Vucinic, who has always been terribly inconsistent, infact the only time he found any consistency was his last three seasons with Roma, when he scored 11, 14, and 10 goals respectively. With those last 10 goals coming in 28 games compared to Quag's 9 in 17 appearances with Juventus in the same season. To say, Quag has nothing over Vucinic is a bit harsh. He is the more consistent player, has better off the ball movement, is certainly more dynamic and falls a lot deeper to help the team in its overall play. Vucinic on the other hand has had 11 seasons in Serie A, excluding the 1 season he spent in Serie B with Lecce.
He can and there were many half seasons when he was doing that for Roma. Quag was carrying the team together with Krasic. Fluke half season. Never happened before and will hardly happen again for both Quag and Krasic.
Again, the key word like you said here is 'half season'. He has never been consistent enough to carry a team. Also, its a little unfair to call Quag's form last season a fluke, because the only season that stands out in Vucinic's career is his 19 goal season with Lecce. You'll notice he's never ever come close to that ever again. Fluke full season?! Vucinic's figures from 2000, stand at: 0, 0, 5 (Serie B), 1, 19, 9, 2, 9, 11, 14, 10, 4(Juventus). Quagliarella's stats from the 05-06 season when he started his Serie A career with Ascoli: 3, 13, 12, 13, 11, 9(17), 2(started only 5 games, and he couldve had another if Licht didnt block his shot against Cesena since you think Napoli was an easy miss) the last two seasons being at Juventus. So if you consider how these numbers stack up head to head, you'll find Quag outscores Vucinic 63 goals to 59 (including the current season) from the time that he has been in the Serie A.
That's an assumption. Just like assuming that if Quag had Vucinic's luck and played all the time we might not have even been so high in the standings because Quag was gonna replace Matri and he wasn't gonna score as much as him. Or if he replaced Vucinic in the 4-3-3 we were gonna be a laughing stock and fight for europa league.
It shouldn't even be a Quag vs Vucinic when we talk about a 4-3-3. It's Giac or Esti vs Vucinic and Quag vs Matri or Borriello.
Its not an assumption actually. Purely going on game time, Quag's strike rate of 2 goals in 5 starts implies he has a better hit rate when compared to Vucinic's 4 goals in 21 starts. When our main concern is goals up front, as has been the case for close to two months, Quag and Matri and even Alex need to be getting the most game time. I've said this before and ill say it again, the 433 is the only saving grace for Vuci. To say he has played wide left and scored a lot of goals playing that position does not discount his responsibility as a forward, whose primary job is to score goals.
You're right that Quag and Vucinic don't replace each other in the 433. Like you said, Giac, Esti, Elia and even Alex, are contending for that wide forward role. But my point is something else. I feel Quag cannot be any less effective than Vucinic in the current scheme of things, and seeing how effective he is as player and has been for us in the past, its about time he got a fair run of games to prove that. Same goes for Alex, and Elia who despite being an unknown quantity needs to be thrown in to the mix so we give our self a fair chance of breaking out of this goal drought.
To judge substitute appearances dont give a fair reflection of a player's overall potential and ability and certainly not when they have 10, 12 and 15 or so minutes of game time every third weekend. An optimal substitution is when a player has about 30 minutes to get to the pace of the game and find their own rhythm. Its evident Boriello doesnt belong here. And hes already got 3 starts ahead of Matri, Quag and Alex. These people need to see a lot more game time to put all the assumptions you or I may have, to rest.