Metabolism and evolutionary rates are linked, but not in the way you describe.
First consider that metabolism is intrinsically linked to body size. The larger an animal is, the smaller amount of energy per unit mass it takes to maintain that body. This can then be extended to many things about an organism, such as life span, gestation time, population growth, etc. (see Brown et al. 2004 for more detail).
Next consider that metabolism changes with temperature. Take an ectotherm (an organism who's internal temperature is the same as the ambient environment, traditionally called cold-blooded creatures) like a lizard, which will go thru temperature fluctuations throughout the day. It will have higher metabolism when the temperature is higher. A lizard living in a warm environment like the tropics will have an overall higher metabolism than a lizard of the same size living in a temperate climate. With that higher metabolism comes a different life span, gestation time, population growth, etc. even though their body sizes are the same.
When temperature is considered and corrected for, all organisms have attributes that scale directly with body size. A plant literally has the same metabolic rate as a lizard if they are a similar mass and live at the same temperatures. (Seriously, see the Brown paper).
Now onto evolution. Rates of evolution depend on many things, but primarily two. Generation time (the time for 1 generation of a population to reproduce) and mutation rates of DNA.
A longer generation time decreases the rate of evolution. For example a single celled organism reproducing every month will evolve faster than an elephant reproducing every decade.
Larger rates of mutation in DNA increase the rate of evolution. If DNA does not change then evolution cannot happen. So the faster DNA changes (thru mutation rates) the faster the potential evolution can be.
Generation time increases with increased body size/metabolism (Brown et al. 2004). Mutation rates decrease with increased size/metabolism (Gillooly et al. 2005).
With those two general patterns, one can say that the rate of evolution decreases with increased metabolism.
Now onto dinosaur evolution. You said that R. Bakker observed that dinosaurs had a higher rate of evolution than expected. With the hypothesis that a higher metabolism caused this. I'll assume they had the same physiological constraints as animals of today, which is reasonable considering they are ancestors of birds. Which everything I just laid out I would propose R. Bakker hypothesis is false, since a higher metabolism means a higher generation time and lower mutation rates, which would lead to decreased rate of evolution.
The latest science says that dinosaurs were endothermic (regulate their own temperature) up to a point (Witze 2014), so their internal temperatures were not as warm as mammals, but probably warmer than most fish and reptiles.
So when accounting for size they likely had lower evolutionary rates than mammals, and higher rates than fish, reptiles, insects, or other ectotherms.
Why then does R. Bakker observe higher evolutionary rates in the fossil record then? I can think of just a general reason why. The timescale of dinosaurs is on the order of 10's of millions of years. Much longer than the tiny amounts of evolution that we have observed in the past 100 years of science. There could easily be processes happening at those long time scales that we aren't considering.
References
Brown, J. H., Gillooly, J. F., Allen, A. P., Savage, V. M., & West, G. B. (2004). Toward a metabolic theory of ecology. Ecology, 85(7), 1771-1789.Link
Gillooly, J. F., Allen, A. P., West, G. B., & Brown, J. H. (2005). The rate of DNA evolution: effects of body size and temperature on the molecular clock. Proceedings of the National Academy of Sciences of the United States of America, 102(1), 140-145. Link
Witze, Alexandra (2014). Dinosaurs neither warm-blooded nor cold-blooded. Nature. 2014 Link
