If, for example, I adjust the variable capacitor on the Alex Loop to obtain the lowest SWR for 14.065 as shown by the Alex tune/818nd meter combination, the Rigexpert will show an SWR at that frequency of about 2.0. The Rigexpert shows a lowest SWR (about 1.2:1) at about 14.082.
On 20 meters, the Alex Loop will give a range of about 20 kHz where the SWR is 1.5 or less. This is significant for me because it enables me to operate over a range of, say, 14.025 to 14.045 without retuning the Alex loop. I use that frequency range in the weekly CWT sessions that CWOps puts on. So, it is important for me to know the actual Alex loop capacitor adjustment for the lowest SWR in the middle of that range. If I have an SWR of 2.0 at 14.035, then a significant portion of the 14.025-14.045 range will have a too high SWR. (For the CWT sessions, I like to stay at 14.025 to 14.045. On weekends, I like to hang out at 14.050-14.070.)