There was a 69% drop in death sentences, from 48 in 1999 to 15 in 2005, PRIOR to LWOP having any effect on death sentences.
The first year that the LWOP law could have had an effect on death sentences was in 2006, with 11 death sentences.
In 2007, death sentences rose by 36%.
With almost total consistency, death sentences averaged a little over 10 per year from 2006-2014, which added an additional 10% drop, to 79%, from the 69% decline of 1999-2005, with that 10%, easily, seen as part of a consistent 15 year (1999-2014) downward trend, unaffected by LWOP.
Death sentences dropped in 2015 and 2016, to 2 and 4, respectively, 10 years after the LWOP law, with no reason to suggest that LWOP was the reason for those numbers, after a 10 year wait, when none of the immediate, previous 15 year, 79% drop can be connected to LWOP. In fact, the reduction of death sentences dropped, dramatically, about 90%/yr., from 2006-2014, after the LWOP became law.
It is important to note that juries were not allowed to be told that the previous life sentences in Texas had parole eligibility.