Unless I'm mistaken, the performance numbers you are citing and linking are based on multithreaded applications...which is not what the Intel graph is about (single-threaded IPC).
 
Am I missing something?
		
		
	 
I understand what you are saying but do you use CPUs in a theoretical sense or in a practical sense? What games are single-threaded? What programs are single threaded now? ITunes? Just because you are testing a dual-threaded game like Starcraft 2 on a quad-core CPU, it doesn't mean you are not stressing the IPC of the CPU in that particular app. I can't play single-threaded Starcraft 2 game since there is no such game. 
You are missing IPC increases in real world apps, not in some chart Intel made without telling us what programs, how many of such programs and from what year the apps they used to arrive at their results. I am sure you can feel comfortable that IPC increases from Conroe to Nehalem at least 10% because Intel has made such a claim. However, if in 20-30 modern applications the average is more like 17-20%, as users of such processors we see 17-20%, not 10%. 
I linked for you IPC increases based on real world applications people may use who buy $200-300 CPUs. I have no idea how Intel derived those numbers but since I've been following IPC increases from real world reviews from Conroe to Nehalem to SB, the #s you posted don't match any review I've ever read on this subject.  The example you cited only has a 10% IPC increase from Conroe to Nehalem and just 7% from Nehalem to SB. This is grossly inaccurate from the performance users see right now if they were to upgrade from a Core 2 Quad to a Core i5 2500K and tested the performance at the same clocks. Are you suggesting that going from Core Q6600 @ 3.2ghz to Core i5 2500K @ 3.2ghz only improves overall performance by 1.10 (C2Q -> Nehalem) *1.07 (Nehalem -> SB) = 17.7%? Q6600's IPC is only on par with Phenom II X4 955-965.
Now look at what happens in CPU limited games between i5 2500K and X4 955 at similar clocks:
		
		
	
	
Perhaps Intel may have used outdated programs/benchmarks when it arrived at those numbers. If you want a true reflection of IPC how a user experiences it, you should benchmark modern apps that have modern code which runs faster on new generation of CPUs due to their inherent architectural enhancement that are better catered for executing modern code. 
For example, how did Intel arrive at IPC increase from Conroe to Nehalem? Did they use 2011-2012 programs or 2008 ones when Nehalem just came out? If they tested games, did they use a 2008 GPU with Nehalem? If so, maybe Nehalem was GPU bottlenecked. Furthermore, why would you ignore IPC increase in multi-threaded apps when discussing overall increase in IPC from one generation to the next? With a relatively modern GPU, you can exploit Nehalem's CPU to the fullest and reveal serious bottlenecks in older architectures such as 
lack of sufficient or slow cache. If you run a 4-threaded app on a quad core CPU, are you not testing IPC? If there are inefficiencies in shared L2/L3 cache of the CPU architecture and its ability to fully feed all the 4 cores in a 4-threaded app, it will show up as a performance hit. 
Trying to graph Intel's IPC increases in limited theoretical single threaded apps is not a true reflection of IPC increases users actually see and feel in modern apps. For that real world benchmarks should be used. Based on real world usage, IPC from Core 2 Quad to Nehalem seems to have increased by 20%, Nehalem to SB is an increase of 14-16%, and SB to IVB is 3-4% --- all at the same clock speed.
Maybe I don't understand the definition of IPC from a technical perspective you are describing and confusing Performance Per Core with IPC? Sorry if I did 

. The way I look at it, if I get a Haswell CPU, how much faster will it be on average in modern apps @ 4.5ghz compared to an i5 2500K @ 4.5ghz? If it's only 10%, it would end up being the lowest real world increase in IPC/per core performance compared to C2Q --> Nehalem --> SB. 
Granted by the same account, Haswell's IPC increase could grow beyond 10% if more programs start using AVX2 and benefit from doubling of the floating point operations. Perhaps I am jumping the gun then and not giving Haswell the chance to shine in more modern apps that will take advantage of its architecture. Maybe Intel just has a tendency to underestimate their real world IPC increases? I guess I'll wait for real world tests before burring Haswell's 10% claim as disappointing as of now. Fair enough.